The Caspian Sea is the world's largest inland

body of water A body of water or waterbody is any significant accumulation of water on the surface of Earth or another planet. The term most often refers to oceans, seas, and lakes, but it includes smaller pools of water such as ponds, wetlands, or more rare ...

, described as the world's largest lake and usually referred to as a full-fledged

sea A sea is a large body of salt water. There are particular seas and the sea. The sea commonly refers to the ocean, the interconnected body of seawaters that spans most of Earth. Particular seas are either marginal seas, second-order section ...

. An

endorheic basin An endorheic basin ( ; also endoreic basin and endorreic basin) is a drainage basin that normally retains water and allows no outflow to other external bodies of water (e.g. rivers and oceans); instead, the water drainage flows into permanent ...

, it lies between

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

and

Asia Asia ( , ) is the largest continent in the world by both land area and population. It covers an area of more than 44 million square kilometres, about 30% of Earth's total land area and 8% of Earth's total surface area. The continent, which ...

: east of the

Caucasus The Caucasus () or Caucasia (), is a region spanning Eastern Europe and Western Asia. It is situated between the Black Sea and the Caspian Sea, comprising parts of Southern Russia, Georgia, Armenia, and Azerbaijan. The Caucasus Mountains, i ...

, west of the broad

steppe In physical geography, a steppe () is an ecoregion characterized by grassland plains without closed forests except near rivers and lakes. Steppe biomes may include: * the montane grasslands and shrublands biome * the tropical and subtropica ...

Central Asia Central Asia is a region of Asia consisting of Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, and Uzbekistan. The countries as a group are also colloquially referred to as the "-stans" as all have names ending with the Persian language, Pers ...

, south of the fertile plains of

Southern Russia Southern Russia or the South of Russia ( rus, Юг России, p=juk rɐˈsʲiɪ) is a Colloquialism, colloquial term for the southernmost geographic portion of European Russia. The term is generally used to refer to the region of Russia's So ...

Eastern Europe Eastern Europe is a subregion of the Europe, European continent. As a largely ambiguous term, it has a wide range of geopolitical, geographical, ethnic, cultural and socio-economic connotations. Its eastern boundary is marked by the Ural Mountain ...

, and north of the mountainous

Iranian Plateau The Iranian plateau or Persian plateau is a geological feature spanning parts of the Caucasus, Central Asia, South Asia, and West Asia. It makes up part of the Eurasian plate, and is wedged between the Arabian plate and the Indian plate. ...

. It covers a surface area of (excluding the highly saline lagoon of Garabogazköl to its east), an area approximately equal to that of

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

, with a volume of . It has a

salinity Salinity () is the saltiness or amount of salt (chemistry), salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensio ...

of approximately 1.2% (12 g/L), about a third of the salinity of average

seawater Seawater, or sea water, is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% (35 g/L, 35 ppt, 600 mM). This means that every kilogram (roughly one liter by volume) of seawater has approximat ...

. It is bounded by

Kazakhstan Kazakhstan, officially the Republic of Kazakhstan, is a landlocked country primarily in Central Asia, with a European Kazakhstan, small portion in Eastern Europe. It borders Russia to the Kazakhstan–Russia border, north and west, China to th ...

to the northeast,

Russia Russia, or the Russian Federation, is a country spanning Eastern Europe and North Asia. It is the list of countries and dependencies by area, largest country in the world, and extends across Time in Russia, eleven time zones, sharing Borders ...

to the northwest,

Azerbaijan Azerbaijan, officially the Republic of Azerbaijan, is a Boundaries between the continents, transcontinental and landlocked country at the boundary of West Asia and Eastern Europe. It is a part of the South Caucasus region and is bounded by ...

to the southwest,

Iran Iran, officially the Islamic Republic of Iran (IRI) and also known as Persia, is a country in West Asia. It borders Iraq to the west, Turkey, Azerbaijan, and Armenia to the northwest, the Caspian Sea to the north, Turkmenistan to the nort ...

to the south, and

Turkmenistan Turkmenistan is a landlocked country in Central Asia bordered by Kazakhstan to the northwest, Uzbekistan to the north, east and northeast, Afghanistan to the southeast, Iran to the south and southwest and the Caspian Sea to the west. Ash ...

to the southeast. The name of the Caspian Sea is derived from the ancient

Iranic Iranian peoples, or Iranic peoples, are the collective ethnolinguistic groups who are identified chiefly by their native usage of any of the Iranian languages, which are a branch of the Indo-Iranian languages within the Indo-European langu ...

Caspi people. The sea stretches from north to south, with an average width of . Its gross coverage is and the surface is about below

sea level Mean sea level (MSL, often shortened to sea level) is an mean, average surface level of one or more among Earth's coastal Body of water, bodies of water from which heights such as elevation may be measured. The global MSL is a type of vertical ...

. Its main freshwater

inflow Inflow may refer to: * Inflow (hydrology), the water entering a body of water * Inflow (meteorology) Inflow is the flow of a fluid into a large collection of that fluid. Within meteorology, inflow normally refers to the influx of warmth and mo ...

, Europe's longest river, the

Volga The Volga (, ) is the longest river in Europe and the longest endorheic basin river in the world. Situated in Russia, it flows through Central Russia to Southern Russia and into the Caspian Sea. The Volga has a length of , and a catchment ...

, enters at the shallow north end. Two deep basins form its central and southern zones. These lead to horizontal differences in temperature, salinity, and ecology. The

seabed The seabed (also known as the seafloor, sea floor, ocean floor, and ocean bottom) is the bottom of the ocean. All floors of the ocean are known as seabeds. The structure of the seabed of the global ocean is governed by plate tectonics. Most of ...

in the south reaches below sea level, which is the third-lowest natural non-oceanic depression on Earth after

Baikal Lake Baikal is a rift lake and the deepest lake in the world. It is situated in southern Siberia, Russia between the federal subjects of Irkutsk Oblast to the northwest and the Republic of Buryatia to the southeast. At —slightly larger tha ...

and Tanganyika lakes. With a surface area of , the Caspian Sea is nearly five times as big as

Lake Superior Lake Superior is the largest freshwater lake in the world by surface areaThe Caspian Sea is the largest lake, but is saline, not freshwater. Lake Michigan–Huron has a larger combined surface area than Superior, but is normally considered tw ...

(). The Caspian Sea is home to a wide range of species and is famous for its

caviar Caviar or caviare is a food consisting of salt-cured roe of the family Acipenseridae. Caviar is considered a delicacy and is eaten as a garnish or spread. Traditionally, the term caviar refers only to roe from wild sturgeon in the Caspi ...

and oil industries. Pollution from the oil industry and dams on rivers that drain into it have harmed its ecology. It is predicted that during the 21st century, the depth of the sea will decrease by 9–18 m (30–60 ft) due to

global warming Present-day climate change includes both global warming—the ongoing increase in global average temperature—and its wider effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes ...

and the process of

desertification Desertification is a type of gradual land degradation of Soil fertility, fertile land into arid desert due to a combination of natural processes and human activities. The immediate cause of desertification is the loss of most vegetation. This i ...

, leading to an

ecocide Ecocide (from Greek 'home' and Latin 'to kill') is the destruction of the natural environment, environment by humans. Ecocide threatens all human populations that are dependent on natural resources for maintaining Ecosystem, ecosystems and ensu ...

Etymology

The sea's name stems from Caspi, the ancient people who lived to the southwest of the sea in

Transcaucasia The South Caucasus, also known as Transcaucasia or the Transcaucasus, is a geographical region on the border of Eastern Europe and West Asia, straddling the southern Caucasus Mountains. The South Caucasus roughly corresponds to modern Armenia, ...

Strabo Strabo''Strabo'' (meaning "squinty", as in strabismus) was a term employed by the Romans for anyone whose eyes were distorted or deformed. The father of Pompey was called "Gnaeus Pompeius Strabo, Pompeius Strabo". A native of Sicily so clear-si ...

(died circa AD 24) wrote that "to the country of the Albanians (

Caucasian Albania Caucasian Albania is a modern exonym for a former state located in ancient times in the Caucasus, mostly in what is now Azerbaijan (where both of its capitals were located). The modern endonyms for the area are ''Aghwank'' and ''Aluank'', among ...

, not to be confused with the country of

Albania Albania ( ; or ), officially the Republic of Albania (), is a country in Southeast Europe. It is located in the Balkans, on the Adriatic Sea, Adriatic and Ionian Seas within the Mediterranean Sea, and shares land borders with Montenegro to ...

) belongs also the territory called Caspiane, which was named after the Caspian tribe, as was also the sea; but the tribe has now disappeared". Moreover, the Caspian Gates, part of

Tehran province Tehran province () is one of the 31 provinces of Iran. Its capital is the city of Tehran. Tehran province covers an area of and is located to the north of the central plateau of Iran. It was made a part of the First Region with its secretar ...

, may evince such people migrated to the south. The Iranian city of

Qazvin Qazvin (; ; ) is a city in the Central District (Qazvin County), Central District of Qazvin County, Qazvin province, Qazvin province, Iran, serving as capital of the province, the county, and the district. It is the largest city in the provi ...

shares the root of its name with this common name for the sea. The traditional and medieval Arabic name for the sea was ''Baḥr'' ('sea') ''

Khazar The Khazars ; 突厥可薩 ''Tūjué Kěsà'', () were a nomadic Turkic people who, in the late 6th century CE, established a major commercial empire covering the southeastern section of modern European Russia, southern Ukraine, Crimea, an ...

'', but in recent centuries the common and standard name in Arabic language has become ''Baḥr

'', the Arabized form of Caspian. In modern Russian language, it is known as , ''Kaspiyskoye more''.''Iran'' (5th ed., 2008), by Andrew Burke and Mark Elliott
p. 28
, Lonely Planet Publications, . Some Turkic ethnic groups refer to it with the Caspi(an) descriptor; in Kazakh it is called , ''Kaspiy teñizi'', , . Others refer to it as the ''

sea'': ; , . In all these the first word refers to the historical

Khaganate A khanate ( ) or khaganate refers to historic polity, polities ruled by a Khan (title), khan, khagan, khatun, or khanum. Khanates were typically nomadic Mongol and Turkic peoples, Turkic or Tatars, Tatar societies located on the Eurasian Steppe, ...

, a large empire based to the north of the Caspian Sea between the 7th and 10th centuries. In Iran, the lake is referred to as the ''Mazandaran Sea'' (), after the historic

Mazandaran Province Mazandaran Province (; ) is one of the 31 provinces of Iran. Its capital is the city of Sari. Located along the southern coast of the Caspian Sea and in the adjacent Central Alborz mountain range and Hyrcanian forests, it is bordered clockw ...

at its southern shores. Old Russian sources use the ''Khvalyn'' or ''Khvalis'' Sea () after the name of

Khwarezmia Khwarazm (; ; , ''Xwârazm'' or ''Xârazm'') or Chorasmia () is a large oasis region on the Amu Darya river delta in western Central Asia, bordered on the north by the (former) Aral Sea, on the east by the Kyzylkum Desert, on the south by ...

. Among

Greeks Greeks or Hellenes (; , ) are an ethnic group and nation native to Greece, Greek Cypriots, Cyprus, Greeks in Albania, southern Albania, Greeks in Turkey#History, Anatolia, parts of Greeks in Italy, Italy and Egyptian Greeks, Egypt, and to a l ...

and

Persians Persians ( ), or the Persian people (), are an Iranian ethnic group from West Asia that came from an earlier group called the Proto-Iranians, which likely split from the Indo-Iranians in 1800 BCE from either Afghanistan or Central Asia. They ...

classical antiquity Classical antiquity, also known as the classical era, classical period, classical age, or simply antiquity, is the period of cultural History of Europe, European history between the 8th century BC and the 5th century AD comprising the inter ...

it was the

Hyrcania Hyrcania (; ''Hyrkanía'', Old Persian: 𐎺𐎼𐎣𐎠𐎴 ''Varkâna'',Lendering (1996) Middle Persian: 𐭢𐭥𐭫𐭢𐭠𐭭 ''Gurgān'', Akkadian: ''Urqananu'') is a historical region composed of the land south-east of the Caspian Sea ...

n Sea (Hyranium Mare). Renaissance European maps labelled it as the ''Abbacuch Sea'' (Oronce Fine's 1531 world map), ''Mar de Bachu'' (Ortellius' 1570 map), or ''Mar de Sala'' (the

Mercator 1569 world map The Mercator world map of 1569 is titled (Renaissance Latin for "New and more complete representation of the terrestrial globe properly adapted for use in navigation"). The title shows that Gerardus Mercator aimed to present contemporary know ...

). It was also sometimes called the Kumyk Sea and Tarki Sea (derived from the name of the

Kumyks Kumyks (, ) are a Turkic ethnic group living in Dagestan, Chechnya and North Ossetia. They are the largest Turkic people in the North Caucasus. They traditionally populate the Kumyk Plateau (northern Dagestan and northeastern Chechnya), la ...

and their historical capital

Tarki Tarki (, ; ) formerly also spelled Tarkou and also known as Tarku, is an urban locality (an urban-type settlement) under the administrative jurisdiction of Sovetsky City District of the City of Makhachkala in the Republic of Dagestan, Russi ...

Basin countries

Border countries

North

* *

East

West

South

Physical characteristics

Formation

Paratethys Megalake Infographic 23X 2 EN

The Caspian Sea is at its ''South Caspian Basin'', like the

Black Sea The Black Sea is a marginal sea, marginal Mediterranean sea (oceanography), mediterranean sea lying between Europe and Asia, east of the Balkans, south of the East European Plain, west of the Caucasus, and north of Anatolia. It is bound ...

, a remnant of the ancient Paratethys Sea. Its seafloor is, therefore, a standard oceanic

basalt Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...

and not a continental

granite Granite ( ) is a coarse-grained (phanerite, phaneritic) intrusive rock, intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly coo ...

body. It is estimated to be about 30 million years old, and became landlocked in the

Late Miocene The Late Miocene (also known as Upper Miocene) is a sub-epoch of the Miocene epoch (geology), Epoch made up of two faunal stage, stages. The Tortonian and Messinian stages comprise the Late Miocene sub-epoch, which lasted from 11.63 Ma (million ye ...

, about 5.5 million years ago, due to

tectonic uplift Tectonic uplift is the orogeny, geologic uplift of Earth#Surface, Earth's surface that is attributed to plate tectonics. While Isostasy, isostatic response is important, an increase in the mean elevation of a region can only occur in response to ...

and a fall in

. The Caspian Sea was a comparatively small endorheic lake during the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58 During warm and dry climatic periods, the landlocked sea almost dried up, depositing evaporitic sediments like

halite Halite ( ), commonly known as rock salt, is a type of salt, the mineral (natural) form of sodium chloride ( Na Cl). Halite forms isometric crystals. The mineral is typically colorless or white, but may also be light blue, dark blue, purple, pi ...

that were covered by wind-blown deposits and were sealed off as an

evaporite An evaporite () is a water- soluble sedimentary mineral deposit that results from concentration and crystallization by evaporation from an aqueous solution. There are two types of evaporite deposits: marine, which can also be described as oce ...

sink A sink (also known as ''basin'' in the UK) is a bowl-shaped plumbing fixture for washing hands, dishwashing, and other purposes. Sinks have a tap (faucet) that supplies hot and cold water and may include a spray feature to be used for fas ...

when cool, wet climates refilled the basin. (Comparable evaporite beds underlie the

Mediterranean The Mediterranean Sea ( ) is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean basin and almost completely enclosed by land: on the east by the Levant in West Asia, on the north by Anatolia in West Asia and Southern ...

.) Due to the current inflow of fresh water in the north, the Caspian Sea water is almost fresh in its northern portions, getting more

brackish Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estuari ...

toward the south. It is most saline on the Iranian shore, where the catchment basin contributes little flow. Currently, the mean salinity of the Caspian is one third that of Earth's oceans. The Garabogazköl lagoon, which dried up when water flow from the main body of the Caspian was blocked in the 1980s but has since been restored, routinely exceeds oceanic salinity by a factor of 10.

Geography

The Caspian Sea is the largest inland body of water in the world by area and accounts for 40–44% of the total lake waters of the world, and covers an area larger than

Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...

. The coastlines of the Caspian are shared by

, and

. The Caspian is divided into three distinct physical regions: the Northern, Middle, and Southern Caspian. The Northern–Middle boundary is the

Mangyshlak Mangyshlak or Mangghyshlaq Peninsula (; ) is a large peninsula located in western Kazakhstan. It borders on the Caspian Sea in the west and with the Buzachi Peninsula, a marshy sub-feature of the main peninsula, in the northeast. The Tyuleniy Ar ...

Threshold, which runs through Chechen Island and Cape Tiub-Karagan. The Middle–Southern boundary is the Apsheron Threshold, a sill of tectonic origin between the Eurasian continent and an oceanic remnant, that runs through Chilov Island and Cape Kuuli. The Garabogazköl Bay is the saline eastern inlet of the Caspian, which is part of Turkmenistan and at times has been a lake in its own right due to the isthmus that cuts it off from the Caspian. Differences between the three regions are dramatic. The Northern Caspian only includes the Caspian shelf, and is very shallow; it accounts for less than 1% of the total water volume with an average depth of only . The sea noticeably drops off towards the Middle Caspian, where the average depth is . The Southern Caspian is the deepest, with oceanic depths of over , greatly exceeding the depth of other regional seas, such as the

Persian Gulf The Persian Gulf, sometimes called the Arabian Gulf, is a Mediterranean seas, mediterranean sea in West Asia. The body of water is an extension of the Arabian Sea and the larger Indian Ocean located between Iran and the Arabian Peninsula.Un ...

. The Middle and Southern Caspian account for 33% and 66% of the total water volume, respectively. The northern portion of the Caspian Sea typically freezes in the winter, and in the coldest winters ice forms in the south as well. Over 130 rivers provide inflow to the Caspian, the

Volga River The Volga (, ) is the longest river in Europe and the longest endorheic basin river in the world. Situated in Russia, it flows through Central Russia to Southern Russia and into the Caspian Sea. The Volga has a length of , and a catchment ...

being the largest. A second affluent, the

Ural River The Ural, also known as the Yaik , is a river flowing through Russia and Kazakhstan in the continental border between Europe and Asia. It originates in the southern Ural Mountains and discharges into the Caspian Sea. At , it is the third-longes ...

, flows in from the north, and the Kura River from the west. In the past, the

Amu Darya The Amu Darya ( ),() also shortened to Amu and historically known as the Oxus ( ), is a major river in Central Asia, which flows through Tajikistan, Turkmenistan, Uzbekistan, and Afghanistan. Rising in the Pamir Mountains, north of the Hindu Ku ...

(Oxus) of Central Asia in the east often changed course to empty into the Caspian through a now-desiccated riverbed called the Uzboy River, as did the

Syr Darya The Syr Darya ( ),; ; ; ; ; /. historically known as the Jaxartes ( , ), is a river in Central Asia. The name, which is Persian language, Persian, literally means ''Syr Sea'' or ''Syr River''. It originates in the Tian Shan, Tian Shan Mountain ...

farther north. The Caspian has several small islands, primarily located in the north with a collective land area of roughly . Adjacent to the North Caspian is the

Caspian Depression The Caspian Depression or the Caspian Lowland is a low-lying flatland region encompassing the northern part of the Caspian Sea, the largest enclosed body of water on Earth. It is the larger northern part of the wider Aral–Caspian Depressio ...

, a low-lying region below

. The

s stretch across the northeast coast, while the

Caucasus mountains The Caucasus Mountains * * Azerbaijani: , * * * * * * * * * * * is a mountain range at the intersection of Asia and Europe. Stretching between the Black Sea and the Caspian Sea, they are surrounded by the Caucasus region ...

hug the western shore. The

biomes A biome () is a distinct geographical region with specific climate, vegetation, and animal life. It consists of a biological community (ecology), community that has formed in response to its physical environment and regional climate. In 1935, Art ...

to both the north and east are characterized by cold, continental deserts. Conversely, the climate to the southwest and south are generally warm with uneven elevation due to a mix of highlands and

mountain range A mountain range or hill range is a series of mountains or hills arranged in a line and connected by high ground. A mountain system or mountain belt is a group of mountain ranges with similarity in form, structure, and alignment that have aris ...

s; the drastic changes in climate alongside the Caspian have led to a great deal of

biodiversity Biodiversity is the variability of life, life on Earth. It can be measured on various levels. There is for example genetic variability, species diversity, ecosystem diversity and Phylogenetics, phylogenetic diversity. Diversity is not distribut ...

in the region. The Caspian Sea has numerous islands near the coasts, but none in the deeper parts of the sea.

Ogurja Ada Ogurja Ada (sometimes also spelt "Ogurga") is the largest island in both Turkmenistan and the Caspian Sea by area. Ogurja Island is also widely known by its Russian name Ogurchinskiy Island ''(Ostrov Ogurchinskiy)''. Geography Ogurja is a desert ...

is the largest island. The island is long, with

gazelle A gazelle is one of many antelope species in the genus ''Gazella'' . There are also seven species included in two further genera; '' Eudorcas'' and '' Nanger'', which were formerly considered subgenera of ''Gazella''. A third former subgenus, ' ...

s roaming freely on it. In the North Caspian, the majority of the islands are small and uninhabited, like the Tyuleniy Archipelago, an

Important Bird Area An Important Bird and Biodiversity Area (IBA) is an area identified using an internationally agreed set of criteria as being globally important for the conservation of bird populations. IBA was developed and sites are identified by BirdLife Int ...

(IBA).

Climate

The climate of the Caspian Sea is variable, with the

cold desert climate The desert climate or arid climate (in the Köppen climate classification ''BWh'' and ''BWk'') is a dry climate sub-type in which there is a severe excess of evaporation over precipitation. The typically bald, rocky, or sandy surfaces in desert ...

(BWk),

cold semi-arid climate Cold is the presence of low temperature, especially in the atmosphere. In common usage, cold is often a subjective perception. A lower bound to temperature is absolute zero, defined as 0.00K on the Kelvin scale, an absolute thermodynamic ...

(BSk), and

humid continental climate A humid continental climate is a climatic region defined by Russo-German climatologist Wladimir Köppen in 1900, typified by four distinct seasons and large seasonal temperature differences, with warm to hot (and often humid) summers, and cold ...

(Dsa, Dfa) being present in the northern portions of the Caspian Sea, while the

Mediterranean climate A Mediterranean climate ( ), also called a dry summer climate, described by Köppen and Trewartha as ''Cs'', is a temperate climate type that occurs in the lower mid-latitudes (normally 30 to 44 north and south latitude). Such climates typic ...

(Csa) and

humid subtropical climate A humid subtropical climate is a subtropical -temperate climate type, characterized by long and hot summers, and cool to mild winters. These climates normally lie on the southeast side of all continents (except Antarctica), generally between ...

(Cfa) are present in the southern portions of the Caspian Sea.

Hydrology

The Caspian has characteristics common to both seas and lakes. It is often listed as the world's largest lake, although it is not

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. The term excludes seawater and brackish water, but it does include non-salty mi ...

: the 1.2% salinity classes it with

brackish water Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estuary ...

bodies. It contains about 3.5 times as much water, by volume, as all five of North America's

Great Lakes The Great Lakes, also called the Great Lakes of North America, are a series of large interconnected freshwater lakes spanning the Canada–United States border. The five lakes are Lake Superior, Superior, Lake Michigan, Michigan, Lake Huron, H ...

combined. The

(about 80% of the inflow) and the

discharge into the Caspian Sea, but it has no natural outflow other than by

evaporation Evaporation is a type of vaporization that occurs on the Interface (chemistry), surface of a liquid as it changes into the gas phase. A high concentration of the evaporating substance in the surrounding gas significantly slows down evapora ...

. Thus the Caspian

ecosystem An ecosystem (or ecological system) is a system formed by Organism, organisms in interaction with their Biophysical environment, environment. The Biotic material, biotic and abiotic components are linked together through nutrient cycles and en ...

is a

closed basin Closed may refer to: Mathematics * Closure (mathematics), a set, along with operations, for which applying those operations on members always results in a member of the set * Closed set, a set which contains all its limit points * Closed interval, ...

, with its own sea level history that is independent of the

eustatic Mean sea level (MSL, often shortened to sea level) is an average surface level of one or more among Earth's coastal bodies of water from which heights such as elevation may be measured. The global MSL is a type of vertical datuma standardised ...

level of the world's oceans. The sea level of the Caspian has fallen and risen, often rapidly, many times over the centuries. Some Russian historians, such as

Lev Gumilev Lev Nikolayevich Gumilev (also Gumilyov; ; – 15 June 1992) was a Soviet and Russian historian, ethnologist, anthropologist and translator. He had a reputation for his highly unorthodox theories of ethnogenesis and historiosophy. He was an ...

, claim that the rising of the Caspian in the 10th century caused the coastal towns of

Khazaria The Khazars ; 突厥可薩 ''Tūjué Kěsà'', () were a nomadic Turkic people who, in the late 6th century CE, established a major commercial empire covering the southeastern section of modern European Russia, southern Ukraine, Crimea, an ...

to flood, resulting in the Khazars losing approximately two-thirds of their territory due to flooding. Over the centuries, Caspian Sea levels have changed in synchrony with the estimated discharge of the Volga, which in turn depends on rainfall levels in its vast catchment basin. Precipitation is related to variations in the amount of North Atlantic depressions that reach the interior, and they in turn are affected by cycles of the North Atlantic oscillation. Thus levels in the Caspian Sea relate to atmospheric conditions in the North Atlantic, thousands of kilometres to the northwest. The last short-term sea-level cycle started with a sea-level fall of from 1929 to 1977, followed by a rise of from 1977 until 1995. Since then smaller oscillations have taken place. A study by the Azerbaijan Academy of Sciences estimated that the level of the sea was dropping by more than six centimetres per year due to increased evaporation due to rising temperatures caused by

climate change Present-day climate change includes both global warming—the ongoing increase in Global surface temperature, global average temperature—and its wider effects on Earth's climate system. Climate variability and change, Climate change in ...

Environmental degradation

The

, the longest river in Europe, drains 20% of the European land area and is the source of 80% of the Caspian's inflow. Heavy development in its lower reaches has caused numerous unregulated releases of chemical and biological pollutants. The

UN Environment Programme The United Nations Environment Programme (UNEP) is responsible for coordinating responses to environmental issues within the United Nations system. It was established by Maurice Strong, its first director, after the United Nations Conference on t ...

warns that the Caspian "suffers from an enormous burden of pollution from oil extraction and refining, offshore oil fields, radioactive wastes from nuclear power plants and huge volumes of untreated sewage and industrial waste introduced mainly by the Volga River". The magnitude of

fossil fuel A fossil fuel is a flammable carbon compound- or hydrocarbon-containing material formed naturally in the Earth's crust from the buried remains of prehistoric organisms (animals, plants or microplanktons), a process that occurs within geolog ...

extraction and transport activity in the Caspian also poses a risk to the environment. The island of

Vulf Vulf, or Volf , and also known as Dash Zira ( Azeri: ''Daş Zirə'') or Kichik Zira ''(Kiçik Zirə)'', is an island of Azerbaijan, in the Caspian Sea. The word "Zira" originated in the Arabic word "Jazīra", meaning "island". Vulf is tiny and un ...

off

Baku Baku (, ; ) is the Capital city, capital and List of cities in Azerbaijan, largest city of Azerbaijan, as well as the largest city on the Caspian Sea and in the Caucasus region. Baku is below sea level, which makes it the List of capital ci ...

, for example, has suffered ecological damage as a result of the petrochemical industry; this has significantly decreased the number of species of marine birds in the area. Existing and planned oil and gas pipelines under the sea further increase the potential threat to the environment. The high concentration of

mud volcano A mud volcano or mud dome is a landform created by the eruption of mud or Slurry, slurries, water and gases. Several geological processes may cause the formation of mud volcanoes. Mud volcanoes are not true Igneous rock, igneous volcanoes as th ...

es under the Caspian Sea were thought to be the cause of a fire that broke out 75 kilometers from

on July 5, 2021. The State oil company of Azerbaijan

SOCAR The State Oil Company of the Republic of Azerbaijan (), largely known by its abbreviation SOCAR, is a fully state-owned national oil and gas company headquartered in Baku, Azerbaijan. The company produces oil and natural gas from onshore and o ...

said preliminary information indicated it was a mud volcano which spewed both mud and flammable gas. It is calculated that during the 21st century, the water level of the Caspian Sea will decrease by 9–18 m (30–60 ft) due to the acceleration of evaporation due to

and the process of

, causing an

. On October 23, 2021, Kazakhstan President

Kassym-Jomart Tokayev Kassym-Jomart Kemeluly Tokayev (born 17 May 1953) is a Kazakhstani politician and diplomat who has served as the second president of Kazakhstan since 2019. He previously served as Prime Minister of Kazakhstan, Prime Minister from 1999 to 2002 ...

signed the Protocol for the Protection of the Caspian Sea against Pollution from Land-based Sources in order to ensure better protection for the biodiversity of the Caspian Sea.

Flora and fauna

Flora

The rising level of the Caspian Sea between 1995 and 1996 reduced the number of habitats for rare species of aquatic vegetation. This has been attributed to a general lack of seeding material in newly formed coastal

lagoon A lagoon is a shallow body of water separated from a larger body of water by a narrow landform, such as reefs, barrier islands, barrier peninsulas, or isthmuses. Lagoons are commonly divided into ''coastal lagoons'' (or ''barrier lagoons'') an ...

s and water bodies. Many rare and endemic plant species of Russia are associated with the tidal areas of the

Volga delta The Volga Delta is the largest river delta in Europe and occurs where Europe's largest river system, the Volga River, drains into the Caspian Sea in Russia's Astrakhan Oblast, north-east of the republic of Kalmykia. The delta is located in the ...

and

riparian forest A riparian forest or riparian woodland is a forested or wooded area of land adjacent to a body of water such as a river, stream, pond, lake, marshland, estuary, canal, Sink (geography), sink, or reservoir. Due to the broad nature of the definitio ...

s of the

Samur River The Samur (; ; ; ) is a river in Russia's Dagestan Republic, also partially flowing through Azerbaijan and forming part of the Azerbaijan–Russia border. Overview The Samur river originates in glaciers and mountain springs of the Greater Cauca ...

delta. The shoreline is also a unique refuge for plants adapted to the loose sands of the Central Asian Deserts. The principal limiting factors to successful establishment of plant species are hydrological imbalances within the surrounding deltas,

water pollution Water pollution (or aquatic pollution) is the contamination of Body of water, water bodies, with a negative impact on their uses. It is usually a result of human activities. Water bodies include lakes, rivers, oceans, aquifers, reservoirs and ...

, and various land reclamation activities. The water level change within the Caspian Sea is an indirect reason for which plants may not get established. These affect aquatic plants of the Volga Delta, such as '' Aldrovanda vesiculosa'' and the native '' Nelumbo caspica''. About 11 plant species are found in the Samur River delta, including the unique

liana A liana is a long-Plant stem, stemmed Woody plant, woody vine that is rooted in the soil at ground level and uses trees, as well as other means of vertical support, to climb up to the Canopy (biology), canopy in search of direct sunlight. T ...

forests that date back to the

Tertiary period The Tertiary ( ) is an obsolete Period (geology), geologic period spanning 66 million to 2.6 or 1.8 million years ago. The period began with the extinction of the non-bird, avian dinosaurs in the Cretaceous–Paleogene extinction event, at t ...

. Since 2019

UNESCO The United Nations Educational, Scientific and Cultural Organization (UNESCO ) is a List of specialized agencies of the United Nations, specialized agency of the United Nations (UN) with the aim of promoting world peace and International secur ...

has admitted the lush

Hyrcanian forests The Hyrcanian forests (; ) are a zone of lush lowland and montane forests covering about near the shores of the Caspian Sea in Iran and Azerbaijan. The forest is named after the ancient region of Hyrcania. The World Wide Fund for Nature refers t ...

Mazandaran Mazandaran Province (; ) is one of the 31 provinces of Iran. Its capital is the city of Sari, Iran, Sari. Located along the southern coast of the Caspian Sea and in the adjacent Central Alborz mountain range and Hyrcanian forests, it is border ...

, Iran as World Heritage Site under category (ix).

Fauna

The

Caspian turtle The Caspian turtle (''Mauremys caspica''), also known as the striped-neck terrapin, is a species of turtle in the family (biology), family Geoemydidae (=Bataguridae). It is found in west Asia, in Iran and central Turkey, northward to the Republic ...

(''Mauremys caspica''), although found in neighboring areas, is a wholly freshwater species. The

zebra mussel The zebra mussel (''Dreissena polymorpha'') is a small freshwater mussel, an Aquatic animal, aquatic bivalve mollusk in the family Dreissenidae. The species originates from the lakes of southern Russia and Ukraine, but has been accidentally Intro ...

is native to the Caspian and

basins, but has become an

invasive species An invasive species is an introduced species that harms its new environment. Invasive species adversely affect habitats and bioregions, causing ecological, environmental, and/or economic damage. The term can also be used for native spec ...

elsewhere, when introduced. The area has given its name to several species, including the

Caspian gull The Caspian gull (''Larus cachinnans'') is a large gull and a member of the herring and lesser black-backed gull complex. The scientific name is from Latin. ''Larus'' appears to have referred to a gull or other large seabird, and ''cachinnans'' ...

and the

Caspian tern The Caspian tern (''Hydroprogne caspia'') is a species of tern, with a subcosmopolitan but scattered distribution. Despite its extensive range, it is monotypic of its genus, and has no accepted subspecies. The genus name is from Ancient Greek '' ...

. The

Caspian seal The Caspian seal (''Pusa caspica'', syn. ''Phoca caspica'') is one of the smallest members of the earless seal family and unique in that it is found exclusively in the brackish Caspian Sea. It lives along the shorelines, but also on the many ro ...

(''Pusa caspica'') is the only aquatic mammal

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to the Caspian Sea, being one of very few seal species that live in inland waters, but it is different from those inhabiting freshwaters due to the hydrological environment of the sea. A century ago the Caspian was home to more than one million

seals Seals may refer to: * Pinniped, a diverse group of semi-aquatic marine mammals, many of which are commonly called seals, particularly: ** Earless seal, or "true seal" ** Fur seal * Seal (emblem), a device to impress an emblem, used as a means of a ...

. Today, fewer than 10% remain. Archeological studies of Gobustan Rock Art have identified what may be oceanic species including

cetaceans Cetacea (; , ) is an infraorder of aquatic mammals belonging to the order Artiodactyla that includes whales, dolphins and porpoises. Key characteristics are their fully aquatic lifestyle, streamlined body shape, often large size and exclusively c ...

from

baleen whale Baleen whales (), also known as whalebone whales, are marine mammals of the order (biology), parvorder Mysticeti in the infraorder Cetacea (whales, dolphins and porpoises), which use baleen plates (or "whalebone") in their mouths to sieve plankt ...

s to

dolphin A dolphin is an aquatic mammal in the cetacean clade Odontoceti (toothed whale). Dolphins belong to the families Delphinidae (the oceanic dolphins), Platanistidae (the Indian river dolphins), Iniidae (the New World river dolphins), Pontopori ...

s, and

auk Auks or alcids are birds of the family Alcidae in the order Charadriiformes. The alcid family includes the Uria, murres, guillemots, Aethia, auklets, puffins, and Brachyramphus, murrelets. The family contains 25 extant or recently extinct speci ...

s most likely

Brunnich's Guillemot The thick-billed murre or Brünnich's guillemot (''Uria lomvia'') is a bird in the auk family (Alcidae). This bird is named after the Danish zoologist Morten Thrane Brünnich. The very deeply black North Pacific subspecies ''Uria lomvia arra'' is ...

, although the rock art on Kichikdash Mountain which is assumed to depict either a

beaked whale Beaked whales (systematic name Ziphiidae) are a Family (biology), family of cetaceans noted as being one of the least-known groups of mammals because of their deep-sea habitat, reclusive behavior and apparent low abundance. Only three or four of ...

or a

, it may represent the famous

beluga sturgeon The beluga (), also known as the beluga sturgeon or great sturgeon (''Huso huso''), is a species of anadromous fish in the sturgeon family (Acipenseridae) of the order Acipenseriformes. It is found primarily in the Caspian and Black Sea basins, ...

instead due to its size (430 cm in length). These

petroglyph A petroglyph is an image created by removing part of a rock surface by incising, picking, carving, or abrading, as a form of rock art. Outside North America, scholars often use terms such as "carving", "engraving", or other descriptions ...

s may suggest potential presences of oceanic faunas in the Caspian Sea presumably until the

Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS), as well as the current and most recent of the twelve periods of the ...

or even the last glacial period or

antiquity Antiquity or Antiquities may refer to: Historical objects or periods Artifacts *Antiquities, objects or artifacts surviving from ancient cultures Eras Any period before the European Middle Ages (5th to 15th centuries) but still within the histo ...

due to historic marine inflow between the current Caspian Sea and either the

Arctic Ocean The Arctic Ocean is the smallest and shallowest of the world's five oceanic divisions. It spans an area of approximately and is the coldest of the world's oceans. The International Hydrographic Organization (IHO) recognizes it as an ocean, ...

North Sea The North Sea lies between Great Britain, Denmark, Norway, Germany, the Netherlands, Belgium, and France. A sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the Norwegian Se ...

, or the

. This is supported by the existences of current endemic, oceanic species such as lagoon cockles which was genetically identified to originate in the Caspian and Black Seas regions. The sea's basin (including associated waters such as rivers) has 160 native species and

subspecies In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...

of fish in more than 60

genera Genus (; : genera ) is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses. In binomial nomenclature, the genus name forms the first part of the binomial s ...

.Naseka, A.M. and Bogutskaya, N.G. (2009). "Fishes of the Caspian Sea: zoogeography and updated check-list". ''Zoosystematica Rossica'' 18(2): 295–317. About 62% of the species and subspecies are

, as are 4–6 genera (depending on

taxonomic 280px, Generalized scheme of taxonomy Taxonomy is a practice and science concerned with classification or categorization. Typically, there are two parts to it: the development of an underlying scheme of classes (a taxonomy) and the allocation ...

treatment). The lake proper has 115 natives, including 73 endemics (63.5%). Among the more than 50 genera in the lake proper, 3–4 are endemic: ''

Anatirostrum The duckbill pugolovka (''Anatirostrum profundorum'') is a species of gobiid fish endemic to the southern part of the Caspian Sea. It is characterized by its special flattened and elongated head that resembles a duck's bill.Brian W. CoadFreshwat ...

'', ''

Caspiomyzon ''Caspiomyzon'' is a genus of lamprey in the family Petromyzontidae. They are native to Eastern Europe and parts of Western and Central Asia. Two of the three species in the genus are endemic to Greece. Taxonomy Species There are currently ...

'', '' Chasar'' (often included in ''

Ponticola ''Ponticola'' is a genus of gobies native mostly to fresh waters of the Black Sea - Caspian Sea region in Eurasia. Some species occur in the brackish-water Black and Caspian seas themselves. It was considered to be part of the broader goby subfam ...

'') and '' Hyrcanogobius''. By far the most numerous families in the lake proper are

gobies Gobiidae or gobies is a family of bony fish in the order Gobiiformes, one of the largest fish families comprising over 2,000 species in more than 200 genera. Most of gobiid fish are relatively small, typically less than in length, and the fam ...

(35 species and subspecies),

cyprinid Cyprinidae is a Family (biology), family of freshwater fish commonly called the carp or minnow family, including the carps, the true minnows, and their relatives the barb (fish), barbs and barbel (fish), barbels, among others. Cyprinidae is the ...

s (32) and

clupeid Clupeidae is a family of clupeiform ray-finned fishes, comprising, for instance, the herrings and sprats. Many members of the family have a body protected with shiny cycloid (very smooth and uniform) scales, a single dorsal fin, and a fusiform ...

s (22). Two particularly rich genera are ''

Alosa ''Alosa'' is a genus of fish, the river herrings, in the family Alosidae. Along with other genera in the subfamily Alosinae, they are generally known as shads. tp://ftp.fao.org/docrep/fao/009/ac482e/ac482e27.pdf Subfamily AlosinaeFAO Fisherie ...

'' with 18 endemic species/subspecies and ''

Benthophilus The tadpole-gobies (''Benthophilus''), also called pugolovkas (which means "tadpole" in Russian), are a genus of Ponto-Caspian fish in the family Gobiidae. They are distributed in the fresh and brackish waters of basins of the Black Sea, Caspi ...

'' with 16 endemic species. Other examples of endemics are four species of '' Clupeonella'', '' Gobio volgensis'', two ''

Rutilus ''Rutilus'', commonly known as roaches, is a genus of freshwater ray-finned fish belonging to the family Leuciscidae, which includes the daces, Eurasian minnows and related fishes. This genus is a widely distributed lineage of leuciscids and r ...

'', three '' Sabanejewia'', ''

Stenodus leucichthys ''Stenodus leucichthys'', also known as the inconnu, sheefish, ''ak balyk'', or ''beloribitsa'', is a species of large, anadromous, freshwater whitefish in the family Salmonidae. In the strict sense its natural distribution is restricted to the ...

'', two ''

Salmo ''Salmo'' is a genus of ray-finned fish from the subfamily Salmoninae of family (biology), family Salmonidae, and is part of the tribe (biology), tribe Salmonini along with the sister genera ''Salvelinus'' and ''Salvethymus''. Almost all ''Salmo ...

'', two ''

Mesogobius ''Mesogobius'' is a genus of Gobiidae, native to the basins of the Black and Caspian Seas. Species There are two or three recognized species in this genus:.Brian W. CoadFreshwater Fishes of Iran(accessed 18 Feb 2015) * '' Mesogobius batrachocep ...

'' and three ''

Neogobius ''Neogobius'' is a genus of gobies, native to Black Sea and the Caspian Sea basins. It is part of the broader Benthophilinae subfamily which is also endemic to the same region. Nevertheless, two ''Neogobius'' species have recently turned out to b ...

''. Most non-endemic natives are either shared with the Black Sea basin or widespread

Palearctic The Palearctic or Palaearctic is a biogeographic realm of the Earth, the largest of eight. Confined almost entirely to the Eastern Hemisphere, it stretches across Europe and Asia, north of the foothills of the Himalayas, and North Africa. Th ...

species such as

crucian carp The crucian carp (''Carassius carassius'') is a medium-sized member of the common carp family Cyprinidae. It occurs widely in northern European regions. Its name derives from the Low German ''karusse'' or ''karutze'', possibly from Medieval Lat ...

Prussian carp The Prussian carp, silver Prussian carp or Gibel carp (''Carassius gibelio'') is a member of the family Cyprinidae, which includes many other fish, such as the common carp, goldfish, and the smaller minnows. It is a medium-sized cyprinid, and d ...

common carp The common carp (''Cyprinus carpio''), also known as European carp, Eurasian carp, or simply carp, is a widespread freshwater fish of eutrophic waters in lakes and large rivers in Europe and Asia.Fishbase''Cyprinus carpio'' Linnaeus, 1758/ref>Ark ...

common bream The common bream (''Abramis brama''), also known as the freshwater bream, bream, bronze bream, carp bream or sweaty bream, is a European species of freshwater fish in the family Leuciscidae. It is now considered to be the monotypic, only speci ...

common bleak The bleak or common bleak (''Alburnus alburnus'') is a small freshwater coarse fish of the family Leuciscidae, which includes the minnows, daces and bleaks. The common bleak is found in Europe and Western Asia. Description The body of the ...

, asp,

white bream ''Blicca'' is a monospecific genus of freshwater ray-finned fish belonging to the family Leuciscidae. The only species in the genus is ''Blicca bjoerkna'', the white bream or silver bream. This species is found in Europe and Western Asia. Distr ...

, sunbleak,

common dace The common dace (''Leuciscus leuciscus'') is a species of freshwater and brackish water ray-finned fish from the family Leuciscidae which is native to Europe but which has been introduced to other parts of the world. It is a quarry species for co ...

common roach The roach, or rutilus roach (''Rutilus rutilus''), also known as the common roach, is a fresh- and brackish-water fish of the family Cyprinidae, native to most of Europe and western Asia. Fish called roach can be any species of the genera ''Rut ...

common rudd The common rudd (''Scardinius erythrophthalmus'') is a benthos, bentho-pelagic freshwater Actinopterygii, ray-finned fish belonging to the Family (biology), family Leuciscidae. This species is widely spread in Europe and central Asia, around the ...

European chub ''Squalius cephalus'', the common chub, European chub or simply chub, is a species of freshwater ray-finned fish belonging to the family Leuciscidae, the daces, Eurasian minnows and related fishes. This species is found in Europe where it freq ...

, sichel,

tench The tench or doctor fish (''Tinca tinca'') is a freshwater, fresh- and brackish water, brackish-water fish of the order Cypriniformes found throughout Eurasia from Western Europe including Great Britain, Britain and Ireland east into Asia as far ...

, European weatherfish,

wels catfish The wels catfish ( or ; ''Silurus glanis''), also called sheatfish or just wels, is a large species of catfish native to wide areas of central, southern, and eastern Europe, in the basins of the Baltic, Black and Caspian Seas. It has been intro ...

northern pike The northern pike (''Esox lucius'') is a species of carnivorous fish of the genus ''Esox'' (pikes). They are commonly found in brackish water, moderately salty and fresh waters of the Northern Hemisphere (''i.e.'' holarctic in distribution). T ...

burbot The burbot (''Lota lota''), also known as bubbot, mariah, loche, cusk, freshwater cod, freshwater ling, freshwater cusk, the lawyer, coney-fish, lingcod, or eelpout, is a species of coldwater ray-finned fish native to the subarctic regions of ...

European perch The European perch (''Perca fluviatilis''), also known as the common perch, redfin perch, big-scaled redfin, English perch, Euro perch, Eurasian perch, Eurasian river perch, Hatch, poor man's rockfish or in Anglophone parts of Europe, simply the ...

and

zander The zander (''Sander lucioperca''), sander or pikeperch, is a species of ray-finned fish from the Family (biology), family Percidae, which also includes perch, Gymnocephalus, ruffe and Darter (fish), darter. It is found in freshwater and brackis ...

. Almost 30 non-indigenous, introduced fish species have been reported from the Caspian Sea, but only a few have become established. Six

sturgeon Sturgeon (from Old English ultimately from Proto-Indo-European language, Proto-Indo-European *''str̥(Hx)yón''-) is the common name for the 27 species of fish belonging to the family Acipenseridae. The earliest sturgeon fossils date to the ...

species, the

Russian Russian(s) may refer to: *Russians (), an ethnic group of the East Slavic peoples, primarily living in Russia and neighboring countries *A citizen of Russia *Russian language, the most widely spoken of the Slavic languages *''The Russians'', a b ...

bastard Bastard or The Bastard may refer to: Parentage * Illegitimate child, a child born to unmarried parents, in traditional Western family law ** Bastard, an archaic term used in English and Welsh bastardy laws, reformed in 1926 People * "The Bastard" ...

Persian Persian may refer to: * People and things from Iran, historically called ''Persia'' in the English language ** Persians, the majority ethnic group in Iran, not to be conflated with the Iranic peoples ** Persian language, an Iranian language of the ...

sterlet The sterlet (''Huso ruthenus'') is a relatively small species of sturgeon from Eurasia native to large rivers that flow into the Black Sea, Azov Sea, and Caspian Sea, as well as rivers in Siberia as far east as Yenisei River, Yenisei. Population ...

, starry and

beluga Beluga may refer to: Animals *Beluga (sturgeon) * Beluga whale Vehicles * Airbus Beluga, a large transport airplane * Airbus BelugaXL, a larger transport airplane * Beluga-class submarine, a class of Russian SSA diesel-electric submarine * U ...

, are native to the Caspian Sea. The last of these is arguably the largest freshwater fish in the world. The sturgeon yield

roe Roe, ( ) or hard roe, is the fully ripe internal egg masses in the ovaries, or the released external egg masses, of fish and certain marine animals such as shrimp, scallop, sea urchins and squid. As a seafood, roe is used both as a cooking, c ...

(eggs) that are processed into

Overfishing Overfishing is the removal of a species of fish (i.e. fishing) from a body of water at a rate greater than that the species can replenish its population naturally (i.e. the overexploitation of the fishery's existing Fish stocks, fish stock), resu ...

has depleted a number of the historic fisheries. In recent years, overfishing has threatened the sturgeon population to the point that

environmentalists Environmentalism is a broad philosophy, ideology, and social movement about supporting life, habitats, and surroundings. While environmentalism focuses more on the environmental and nature-related aspects of green ideology and politics, ecologi ...

advocate banning sturgeon fishing completely until the population recovers. The high price of sturgeon caviar—more than 1,500

Azerbaijani manat The manat (ISO 4217, ISO code: AZN; Currency symbol, sign: ₼; abbreviation: m) is the currency of Azerbaijan. It is subdivided into 100 ''gapiks''. The first iteration of the currency emerged in the Azerbaijan Democratic Republic and its succ ...

s (US$880 ) per kilo—allows fishermen to afford bribes to ensure the authorities look the other way, making regulations in many locations ineffective. Caviar harvesting further endangers the fish stocks, since it targets reproductive females. Extantigerturanianwksciam97

Reptile Reptiles, as commonly defined, are a group of tetrapods with an ectothermic metabolism and Amniotic egg, amniotic development. Living traditional reptiles comprise four Order (biology), orders: Testudines, Crocodilia, Squamata, and Rhynchocepha ...

s native to the region include the

spur-thighed tortoise Greek tortoise (''Testudo graeca''), also known as the spur-thighed tortoise or Moorish tortoise, is a species of tortoise in the family Testudinidae. It is a medium sized herbivorous testudinae, widely distributed in the Mediterranean basin, M ...

(''Testudo graeca buxtoni'') and Horsfield's tortoise. *The

Asiatic cheetah The Asiatic cheetah (''Acinonyx jubatus venaticus'') is a critically endangered cheetah subspecies currently only surviving in Iran. Its range once spread from the Arabian Peninsula and the Near East to the Caspian region, Transcaucasus, Kyzyl ...

used to occur in the Trans-Caucasus and

, but is today restricted to Iran.Humphreys, P., Kahrom, E. (1999)
Lion and Gazelle: The Mammals and Birds of Iran
. Images Publishing, Avon. *The

Asiatic lion The Asiatic lion is a lion population of the subspecies ''Panthera leo leo''. Until the 19th century, it occurred in Saudi Arabia, eastern Turkey, Iran, Mesopotamia, and from east of the Indus River in Pakistan to the Bengal region and the Narm ...

used to occur in the Trans-Caucasus, Iran, and possibly the southern part of

Turkestan Turkestan,; ; ; ; also spelled Turkistan, is a historical region in Central Asia corresponding to the regions of Transoxiana and East Turkestan (Xinjiang). The region is located in the northwest of modern day China and to the northwest of its ...

. *The

Caspian tiger The Caspian tiger was a '' Panthera tigris tigris'' population native to eastern Turkey, northern Iran, Mesopotamia, the Caucasus around the Caspian Sea, Central Asia to northern Afghanistan and the Xinjiang region in western China. Until the Midd ...

used to occur in northern Iran, the Caucasus and Central Asia. *The endangered

Persian leopard ''Panthera pardus tulliana'', also called Persian leopard, Anatolian leopard, and Caucasian leopard in different parts of its range, is a leopard subspecies that was first described in 1856 based on a zoological specimen found in western Anato ...

is found in Iran, the Caucasus and Central Asia.

History

Geology

The main geologic history locally had two stages. The first is the

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

, determined by

tectonic Tectonics ( via Latin ) are the processes that result in the structure and properties of the Earth's crust and its evolution through time. The field of ''planetary tectonics'' extends the concept to other planets and moons. These processes ...

events that correlate with the closing of the

Tethys Sea The Tethys Ocean ( ; ), also called the Tethys Sea or the Neo-Tethys, was a prehistoric ocean during much of the Mesozoic Era and early-mid Cenozoic Era. It was the predecessor to the modern Indian Ocean, the Mediterranean Sea, and the Eurasia ...

. The second is the

Pleistocene The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...

noted for its

glaciation A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate be ...

cycles and the full run of the present Volga. During the first stage, the Tethys Sea had evolved into the

Sarmatian The Sarmatians (; ; Latin: ) were a large confederation of Ancient Iranian peoples, ancient Iranian Eurasian nomads, equestrian nomadic peoples who dominated the Pontic–Caspian steppe, Pontic steppe from about the 5th century BCE to the 4t ...

Lake, that was created from the modern Black Sea and south Caspian, when the collision of the

Arabian peninsula The Arabian Peninsula (, , or , , ) or Arabia, is a peninsula in West Asia, situated north-east of Africa on the Arabian plate. At , comparable in size to India, the Arabian Peninsula is the largest peninsula in the world. Geographically, the ...

with

West Asia West Asia (also called Western Asia or Southwest Asia) is the westernmost region of Asia. As defined by most academics, UN bodies and other institutions, the subregion consists of Anatolia, the Arabian Peninsula, Iran, Mesopotamia, the Armenian ...

pushed up the

Kopet Dag The Köpet Dag, Kopet Dagh, or Koppeh Dagh (; ), also known as the Turkmen-Khorasan Mountain Range, is a mountain range on the border between Turkmenistan and Iran that extends about along the border southeast of the Caspian Sea, stretching nort ...

and

Caucasus Mountains The Caucasus Mountains * * Azerbaijani: , * * * * * * * * * * * is a mountain range at the intersection of Asia and Europe. Stretching between the Black Sea and the Caspian Sea, they are surrounded by the Caucasus region ...

, lasting south and west limits to the basin. This orogenic movement was continuous, while the Caspian was regularly disconnected from the

. In the late

Pontian stage Pontian may refer to: * Pope Pontian (died 235), 3rd-century Catholic Pope * Pontian Greeks, a group of ethnic Greeks traditionally from the Pontus and Pontic Mountains regions in northern Turkey * Pontian Islands, a group of islands on the coast o ...

, a mountain arch rose across the south basin and divided it into the Khachmaz and

Lankaran Lankaran (, ) or Lánkon () is a city in Azerbaijan, on the coast of the Caspian Sea, near the southern border with Iran. As of 2021, the city had a population of 89,300. It is next to, but independent of, Lankaran District. The city forms a disti ...

Lakes (or early Balaxani). The period of restriction to the south basin was reversed during the Akchagylian—the lake became more than three times its size today and took again the first of a series of contacts with the Black Sea and

Aral Sea The Aral Sea () was an endorheic lake lying between Kazakhstan to its north and Uzbekistan to its south, which began shrinking in the 1960s and had largely dried up into desert by the 2010s. It was in the Aktobe and Kyzylorda regions of Kazakhst ...

. A recession of Lake Akchagyl completed stage one.

Early settlement nearby

The earliest hominid remains found around the Caspian Sea are from

Dmanisi Dmanisi ( ka, დმანისი, tr, , ) is a town and archaeological site in the Kvemo Kartli region of Georgia (country), Georgia approximately 93 km southwest of the nation’s capital Tbilisi in the river valley of Mashavera. Abandoned i ...

dating back to around 1.8 million years ago and yielded a number of skeletal remains of ''

Homo erectus ''Homo erectus'' ( ) is an extinction, extinct species of Homo, archaic human from the Pleistocene, spanning nearly 2 million years. It is the first human species to evolve a humanlike body plan and human gait, gait, to early expansions of h ...

'' or ''

Homo ergaster ''Homo ergaster'' is an extinct species or subspecies of archaic humans who lived in Africa in the Early Pleistocene. Whether ''H. ergaster'' constitutes a species of its own or should be subsumed into '' H. erectus'' is an ongoing and unresol ...

''. More later evidence for human occupation of the region came from a number of caves in

Georgia Georgia most commonly refers to: * Georgia (country), a country in the South Caucasus * Georgia (U.S. state), a state in the southeastern United States Georgia may also refer to: People and fictional characters * Georgia (name), a list of pe ...

and Azerbaijan such as Kudaro and

Azykh Cave Azykh Cave (), also referred to as Azokh Cave (), is a six-cave complex in Azerbaijan, known as a habitation site of prehistoric humans. It is situated near the village of Azykh in the Khojavend District. The cave is an important prehistoric sit ...

s. There is evidence for

Lower Palaeolithic The Lower Paleolithic (or Lower Palaeolithic) is the earliest subdivision of the Paleolithic or Old Stone Age. It spans the time from around 3.3 million years ago when the first evidence for stone tool production and use by hominins appears ...

human occupation south of the Caspian from western Alburz. These are Ganj Par and

Darband Cave Darband Cave is a Lower Paleolithic site in the Gilan Province in northern Iran, located on the north side of a deep tributary canyon of the Siahrud River, a tributary of the Sefīd-Rūd River that flows into the Caspian Sea. The cave contains e ...

sites.

Neanderthal Neanderthals ( ; ''Homo neanderthalensis'' or sometimes ''H. sapiens neanderthalensis'') are an extinction, extinct group of archaic humans who inhabited Europe and Western and Central Asia during the Middle Pleistocene, Middle to Late Plei ...

remains also have been discovered at a cave in Georgia. Discoveries in the Hotu cave and the adjacent Kamarband cave, near the town of

Behshahr Behshahr () is a city in the Central District of Behshahr County, Mazandaran province, Iran, serving as capital of both the county and the district. It is located at the foot of the Alborz mountains, approximately east of Sari and west of ...

south of the Caspian in Iran, suggest human habitation of the area as early as 11,000 years ago. Ancient Greeks focused on the civilization on the south shore—they call it the (H)yr(c/k)anian Sea (, with sources noting the latter word was evolving then to today's ''Thelessa'': late ).

Hafiz-i Abru Hafez-e AbruMaria Eva Subtelny and Charles Melville, (; died June 1430) was a Persian historian working at the courts of Timurid rulers of Central Asia. His full name is ʿAbdallah (or Nur-Allah) Ebn Lotf-Allah Ebn 'Abd-al-Rashid Behdadini; ...

, a fourteenth century

Timurid Empire The Timurid Empire was a late medieval, culturally Persianate, Turco-Mongol empire that dominated Greater Iran in the early 15th century, comprising modern-day Iran, Iraq, Afghanistan, much of Central Asia, the South Caucasus, and parts of co ...

geographer, recorded that the destruction of the Oxus river dam and irrigation works diverted the river flow towards the Caspian Sea, which caused the Aral sea to nearly disappear.

Chinese maximal limit

Later, in the

Tang dynasty The Tang dynasty (, ; zh, c=唐朝), or the Tang Empire, was an Dynasties of China, imperial dynasty of China that ruled from 618 to 907, with an Wu Zhou, interregnum between 690 and 705. It was preceded by the Sui dynasty and followed ...

(618–907), the sea was the western limit of the Chinese Empire.

Fossil fuel

The area is rich in

fossil fuels A fossil fuel is a flammable carbon compound- or hydrocarbon-containing material formed naturally in the Earth's crust from the buried remains of prehistoric organisms (animals, plants or microplanktons), a process that occurs within geologica ...

. Oil wells were being dug in the region as early as the 10th century to reach oil "for use in everyday life, both for medicinal purposes and for heating and lighting in homes"."The Development of the Oil and Gas Industry in Azerbaijan
". SOCAR By the 16th century, Europeans were aware of the rich oil and gas deposits locally. English traders Thomas Bannister and Jeffrey Duckett described the area around

as "a strange thing to behold, for there issueth out of the ground a marvelous quantity of oil, which serveth all the country to burn in their houses. This oil is black and is called nefte. There is also by the town of Baku, another kind of oil which is white and very precious .e., petroleum">petroleum.html" ;"title=".e., petroleum">.e., petroleum""Back to the Future: Britain, Baku Oil and the Cycle of History
". SOCAR Today, oil and gas platforms abound along the edges of the sea.

Geography, geology and navigation studies

During the rule of Peter I the Great, Fyodor Soimonov was a pioneering explorer of the sea. He was a hydrographer who charted and greatly expanded knowledge of the sea. He drew a set of four maps and wrote ''Pilot of the Caspian Sea'', the first lengthy report and modern maps. These were published in 1720 by the

Russian Academy of Sciences The Russian Academy of Sciences (RAS; ''Rossíyskaya akadémiya naúk'') consists of the national academy of Russia; a network of scientific research institutes from across the Russian Federation; and additional scientific and social units such ...

Cities

Ancient

, ancient state in the north of Iran *

Sari A sari (also called sharee, saree or sadi)The name of the garment in various regional languages include: * * * * * * * * * * * * * * is a drape (cloth) and a women's garment in the Indian subcontinent. It consists of an un-sti ...

of Iran * Anzali,

Gilan Province Gilan Province () is one of the 31 provinces of Iran, in the northwest of the country and southwest of the Caspian Sea. Its capital is the city of Rasht. The province lies along the Caspian Sea, in Iran's Regions of Iran, Region 3, west of ...

of Iran * Astara, Gilan Province of Iran *

Astarabad Gorgan (; ) is a city in the Central District of Gorgan County, Golestan province, Iran, serving as capital of the province, the county, and the district. It lies approximately to the northeast of the national capital Tehran, and some a ...

, Golestan Province of Iran * Tamisheh, Golestan Province of Iran * Atil, Khazaria *

Khazaran Khazaran was a city in the Khazar kingdom, located on the eastern bank of the lower Volga River. It was connected to Atil by a pontoon bridge. Khazaran was later inhabited primarily by Muslims and featured numerous mosques, minarets, and madrasas ...

, Azerbaijan *

Derbent Derbent, also historically known as Darband, or Derbend, is the southernmost city in Russia. It is situated along the southeastern coast of the Dagestan, Republic of Dagestan, occupying the narrow gateway between the Caspian Sea and the Caucas ...

Dagestan Dagestan ( ; ; ), officially the Republic of Dagestan, is a republic of Russia situated in the North Caucasus of Eastern Europe, along the Caspian Sea. It is located north of the Greater Caucasus, and is a part of the North Caucasian Fede ...

, Russia *

Xacitarxan Hajji Tarkhan or Hajji Tarkhan al Jedid (Turki/Cuman language, Kypchak and , ), also known as Hashtar Khan / Astarxan () or Astrakhan, was a medieval city at the right bank of Volga, situated approximately 12 km north of the modern city of A ...

, modern-day

Astrakhan Astrakhan (, ) is the largest city and administrative centre of Astrakhan Oblast in southern Russia. The city lies on two banks of the Volga, in the upper part of the Volga Delta, on eleven islands of the Caspian Depression, from the Caspian Se ...

Modern

: ** Ali Abad ** Astane-ye Ashrafiye ** Astara **

Babolsar Babolsar () is a city in the Central District of Babolsar County, Mazandaran province, Iran, serving as capital of both the county and the district. It is along the Caspian Sea. History Ancient Era Before Islam, Mazandaran Province w ...

Bandar-e Anzali Bandar-e Anzali () is a city on the Caspian Sea in the Central District of Bandar-e Anzali County, Gilan province, Iran, serving as the capital of both the county and the district. History Anzali is an old city in ancient Iran, first s ...

** Bandar-e-Gaz **

Bandar Torkaman Bandar Torkaman () is a city in the Central District of Torkaman County, Golestan province, Iran, serving as capital of both the county and the district. Demographics Population At the time of the 2006 National Census, the city's populati ...

** Chalus ** Fenderesk **

Gomishan Gomish Tappeh () is a city in the Central District of Gomishan County, Golestan province, Iran, serving as capital of both the county and the district. The city's Turkmen name, Kümüş Depe, means "Silver Hill." Demographics Population ...

Gonbad-e Kavus Gonbad-e Kavus () is a city in the Central District of Gonbad-e Kavus County, Golestan Province, Iran, serving as capital of both the county and the district. The modern name, meaning "the tower of Kavus", is a reference to the most impo ...

Gorgan Gorgan (; ) is a city in the Central District (Gorgan County), Central District of Gorgan County, Golestan province, Golestan province, Iran, serving as capital of the province, the county, and the district. It lies approximately to the nor ...

Juybar Juybar () is a city in the Central District of Juybar County, Mazandaran province, Iran, serving as capital of both the county and the district. Juybar is known as the wrestling capital of Iran. Demographics Population At the time of the ...

** Kordkuy **

Lahijan Lahijan () is a city in close proximity to the Caspian Sea within the Central District (Lahijan County), Central District of Lahijan County, in northwestern Iran's Gilan province, Gilan province. It serves as capital of both the county and ...

Langarud Langarud () is a city in the Central District of Langarud County, Gilan province, Iran, serving as capital of both the county and the district. Demographics Population At the time of the 2006 National Census, the city's population was 65, ...

** Mahmudabad **

Neka Neka () is a city in the Central District of Neka County, Mazandaran province, Iran, serving as capital of both the county and the district. History Not much is known about this area in geographical or historical accounts of the past, until ...

Nowshahr Nowshahr () is a city in the Central District of Nowshahr County, Mazandaran province, Iran, serving as capital of both the county and the district. It is a port city on the southern coast of the Caspian Sea. History Ruyan is a region in t ...

** Nur ** Ramsar **

Rasht Rasht (; ) is a city in the Central District (Rasht County), Central District of Rasht County, Gilan province, Gilan province, Iran, serving as the capital of the province, the county, and the district. The city is also known as the "City of ...

Rudbar Rudbar () is a city in the Central District of Rudbar County, Gilan province, Iran, serving as capital of both the county and the district. Etymology Its name (meaning "by the river" in Persian) is a reference to the river Sepid Rood (Se ...

Rudsar Rudsar () is a city in the Central District (Rudsar County), Central District of Rudsar County, Gilan province, Gilan province, Iran, serving as capital of both the county and the district. Etymology The word ''Rudsar'' comes from the wor ...

Sorkhrud Sorkhrud () is a city in, and the capital of, Sorkhrud District of Mahmudabad County, Mazandaran province, Iran Iran, officially the Islamic Republic of Iran (IRI) and also known as Persia, is a country in West Asia. It borders ...

** Talesh **

Tonekabon Tonekabon () is a city in the Central District of Tonekabon County, Mazandaran province, Iran, serving as capital of both the county and the district. Etymology Toneka was a large and fortress-like city with a fence and a hard and stron ...

: ** Astara **

** Gobustan **

Khudat Khudat () is a town in the Caspian lowlands located in the northern section of Azerbaijan. It is a part of the Khachmaz District. It has a population of 14,442. Khudat's time of historical significance took place in the 18th century, as the pro ...

** Khachmaz **

Masallı Masally () is a city in and the capital of the Masally District of Azerbaijan Azerbaijan, officially the Republic of Azerbaijan, is a Boundaries between the continents, transcontinental and landlocked country at the boundary of West Asia ...

Nabran Nabran is a municipality located in the Khachmaz region which is located in Khachmaz Rayon of Azerbaijan, close to the Russia-Azerbaijan border. It has a population of 1,313. The municipality consists of the following villages Nabran, Dalğalı, ...

** Neftchala ** Shabran ** Siyazan **

Oil Rocks An oil is any nonpolar chemical substance that is composed primarily of hydrocarbons and is hydrophobic (does not mix with water) and lipophilic (mixes with other oils). Oils are usually flammable and surface active. Most oils are unsaturat ...

Sumqayit Sumqayit (or Sumgait; ; , ) is a city in Azerbaijan, located near the Caspian Sea, on the Absheron Peninsula, about away from the capital Baku. The city had a population of 427,000 at the beginning of 2024, making it the List of cities in Azerb ...

: **

Atyrau Atyrau (, ; , ; ), known until 1991 as Guryev (), is a city in Kazakhstan and the capital of Atyrau Region. Atyrau is a transcontinental city, at the mouth of the Ural River on the Caspian Sea, between Europe and Asia, west of Almaty and east o ...

Aktau Aktau (; ) is a city in south-west Kazakhstan, on the eastern shore of the Caspian Sea. Aktau is on the Mangyshlak Peninsula in the Mangystau Region. Known for its strategic location on the Caspian Sea, Aktau is a port, playing a key role in th ...

* Russia: **

Dagestanskiye Ogni Dagestanskiye Ogni ( ; ; , ''Dağıstan İşıqları''; ) is a town in the Republic of Dagestan, Russia, located on the coast of the Caspian Sea, south of Makhachkala. Population: Administrative and municipal status Within the framework of a ...

Izberbash Izberbash (; Dargwa: Избир; , ''Yizbirbaş'') is a town in the Republic of Dagestan, Russia, located on the coast of the Caspian Sea southeast of Makhachkala, the capital of the republic. Population: History It was founded in 1932 as an ...

Kaspiysk Kaspiysk (; Lezgin: Каспи ; ) is a city in Dagestan, Russia, located on the Caspian Sea, southeast of Makhachkala. The 2010 Russian census recorded the city as being the fourth-largest in Dagestan. It is a working-class satellite city to ...

Makhachkala Makhachkala, previously known as Petrovskoye (1844–1857) and Port-Petrovsk (1857–1921), or by the local Kumyk language, Kumyk name of Anji, is the capital and List of cities and towns in Russia by population, largest city of Dagestan, Russia. ...

: ** Türkmenbaşy (formerly Krasnovodsk) **

Hazar Hazar may refer to: People * Hazar (name), including a list of people with the name Places * Hazar, Turkmenistan * Hazaran, or Hazar, a mountain in Iran * Hesaruiyeh, or Hazar, Iran * Lake Hazar, Turkey * Hazar, Norway See also * Hezar (disa ...

(formerly Çeleken) **

Esenguly Esenguly (formerly Hasan-Kuly, Gasan-Kuli) is a city in and administrative center of Esenguly District, Balkan Province, Turkmenistan. In 1989 its population was 5,823. Etymology The name is of obscure origin. A clan of that name, part of the ...

Garabogaz Garabogaz () is a city subordinate to Turkmenbashy District, Balkan province, Turkmenistan, on the shore of the Caspian Sea. Until 2002, the municipality had the status of a town and was named ''Bekdaş'' . Etymology The city takes its name f ...

(formerly Bekdaş)

Economy

Countries in the Caspian region, particularly

and

, have high-value natural-resource-based economies, where the oil and gas compose more than 10 percent of their

GDP Gross domestic product (GDP) is a monetary measure of the total market value of all the final goods and services produced and rendered in a specific time period by a country or countries. GDP is often used to measure the economic performance o ...

and 40 percent of their exports. All the Caspian region economies are highly dependent on this type of

mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2011): Mi ...

wealth. The world energy markets were influenced by Azerbaijan and Kazakhstan, as they became strategically crucial in this sphere, thus attracting the largest share of

foreign direct investment A foreign direct investment (FDI) is an ownership stake in a company, made by a foreign investor, company, or government from another country. More specifically, it describes a controlling ownership an asset in one country by an entity based i ...

(FDI). All of the countries are rich in solar energy and harnessing potential, with the highest rainfall much less than the mountains of central Europe in the mountains of the west, which are also rich in

hydroelectricity Hydroelectricity, or hydroelectric power, is Electricity generation, electricity generated from hydropower (water power). Hydropower supplies 15% of the world's electricity, almost 4,210 TWh in 2023, which is more than all other Renewable energ ...

sources.

has high fossil fuel energy potential. It has reserves of 137.5 billion

barrels A barrel or cask is a hollow cylindrical container with a bulging center, longer than it is wide. They are traditionally made of wooden staves and bound by wooden or metal hoops. The word vat is often used for large containers for liquids ...

crude oil Petroleum, also known as crude oil or simply oil, is a naturally occurring, yellowish-black liquid chemical mixture found in geological formations, consisting mainly of hydrocarbons. The term ''petroleum'' refers both to naturally occurring u ...

, the fourth largest in the world, producing around four million barrels a day. Iran has an estimated 988.4 trillion cubic feet of

natural gas Natural gas (also fossil gas, methane gas, and gas) is a naturally occurring compound of gaseous hydrocarbons, primarily methane (95%), small amounts of higher alkanes, and traces of carbon dioxide and nitrogen, hydrogen sulfide and helium ...

, around 16 percent of world reserves, thus key to current paradigms in global energy security.

Russia's economy The economy of Russia is an emerging and developing, high-income, industrialized, mixed market-oriented economy. —Rosefielde, Steven, and Natalia Vennikova. "Fiscal Federalism in Russia: A Critique of the OECD Proposals". ''Cambridge Jour ...

ranks as the twelfth largest by

nominal GDP Gross domestic product (GDP) is a monetary measure of the total market value of all the final goods and services produced and rendered in a specific time period by a country or countries. GDP is often used to measure the economic performance ...

and sixth largest by

purchasing power parity Purchasing power parity (PPP) is a measure of the price of specific goods in different countries and is used to compare the absolute purchasing power of the countries' currency, currencies. PPP is effectively the ratio of the price of a market bask ...

in 2015. Russia's extensive mineral and energy resources are the largest such reserves in the world, making it the second leading producer of oil and

globally. Caspian

littoral The littoral zone, also called litoral or nearshore, is the part of a sea, lake, or river that is close to the shore. In coastal ecology, the littoral zone includes the intertidal zone extending from the high water mark (which is rarely i ...

states join efforts to develop infrastructure, tourism and trade in the region. The first Caspian Economic Forum was convened on August 12, 2019, in Turkmenistan and brought together representatives of Kazakhstan, Russia, Azerbaijan, Iran and that state. It hosted several meetings of their ministers of economy and transport. The Caspian countries develop robust cooperation in the tech and digital field as part of the Caspian Digital Hub. The project helps expand data transmission capabilities in Kazakhstan as well as data transit capabilities between Asia and Europe. The project generated interest from investors from all over the world, including the UK.

Oil and gas

The Caspian Sea region presently is a significant, but not major, supplier of

to world markets, based upon estimates by

BP Amoco BP p.l.c. (formerly The British Petroleum Company p.l.c. and BP Amoco p.l.c.; stylised in all lowercase) is a British multinational oil and gas company headquartered in London, England. It is one of the oil and gas "supermajors" and one of ...

and the U.S.

Energy Information Administration The U.S. Energy Information Administration (EIA) is a principal agency of the U.S. Federal Statistical System responsible for collecting, analyzing, and disseminating energy information to promote sound policymaking, efficient markets, and pub ...

U.S. Department of Energy The United States Department of Energy (DOE) is an executive department of the U.S. federal government that oversees U.S. national energy policy and energy production, the research and development of nuclear power, the military's nuclear we ...

. The region output about 1.4–1.5 million

per day plus natural

gas Gas is a state of matter that has neither a fixed volume nor a fixed shape and is a compressible fluid. A ''pure gas'' is made up of individual atoms (e.g. a noble gas like neon) or molecules of either a single type of atom ( elements such as ...

liquids in 2001, 1.9% of total world output. More than a dozen countries output more than this top figure. Caspian region production has been higher, but waned during and after the collapse of the

Soviet Union The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...

accounts for 55% and

for about 20% of the states' oil output. Caspian region oil and natural gas infrastructure

The world's first offshore wells and machine-drilled wells were made in Bibi-Heybat Bay, near

Baku, Azerbaijan Baku (, ; ) is the Capital city, capital and List of cities in Azerbaijan, largest city of Azerbaijan, as well as the largest city on the Caspian Sea and in the Caucasus region. Baku is below sea level, which makes it the List of capital ci ...

. In 1873, exploration and development of oil began in some of the largest fields known to exist in the world at that time on the

Absheron Peninsula The Absheron Peninsula () is a peninsula in Azerbaijan. It is the location of Baku, the most populous city of the country, and the Baku Metropolitan Area, with its satellite cities Sumqayit and Khyrdalan. It extends eastward into the Caspian S ...

near the villages of Balakhanli,

Sabunchi Sabunchi is a town in the Ararat (province), Ararat Province of Armenia. References

*{{GEOnet2, 32FA881E6B003774E0440003BA962ED3 Populated places in Armenia Yazidi populated places in Armenia ...

, Ramana, and Bibi Heybat. Total recoverable reserves were more than 500 million tons. By 1900, Baku had more than 3,000 oil wells, 2,000 of which were producing at industrial levels. By the end of the 19th century, Baku became known as the "black gold capital", and many skilled workers and specialists flocked to the city. By the beginning of the 20th century, Baku was the center of the international oil industry. In 1920, when the

Bolsheviks The Bolsheviks, led by Vladimir Lenin, were a radical Faction (political), faction of the Marxist Russian Social Democratic Labour Party (RSDLP) which split with the Mensheviks at the 2nd Congress of the Russian Social Democratic Labour Party, ...

captured Azerbaijan, all private property, including oil wells and factories, was confiscated. Rapidly the republic's oil industry came under the control of the

. By 1941, Azerbaijan was producing a record 23.5 million tons of oil per year – its Baku region output was nearly 72 percent of the Soviet Union's oil. In 1994, the "

Contract of the Century The petroleum industry in Azerbaijan produced about 33 million tonnes of oil and 35 billion cubic meters of gas in 2022. Azerbaijan is one of the birthplaces of the oil industry. The State Oil Company of the Republic of Azerbaijan (SOCAR), a fu ...

" was signed, heralding extra-regional development of the Baku oil fields. The large

Baku–Tbilisi–Ceyhan pipeline The Baku–Tbilisi–Ceyhan (BTC) pipeline is a long crude oil pipeline from the Azeri–Chirag–Gunashli oil field in the Caspian Sea to the Mediterranean Sea. It connects Baku, the capital of Azerbaijan and Ceyhan, a port on the south-easte ...

conveys Azeri oil to the Turkish Mediterranean port of

Ceyhan Ceyhan () is a municipality and district of Adana Province, Turkey. Its area is 1,426 km2, and its population is 158,922 (2022). It is the most populous district of the province, outside the city of Adana. Ceyhan is the transportation hub for ...

and opened in 2006. The oil field in the Russian section of the body of water was discovered in 2005. It is reportedly the largest found in 25 years. It was announced in October 2016 that Lukoil would start production from it.

Transport

has the main moorings of all large vessels, such as oil tankers, in

. It is the largest port of the Caspian Sea. The port (and tankers) have access to the oceans along the Caspian Sea–Volga– Don

Canal Canals or artificial waterways are waterways or engineered channels built for drainage management (e.g. flood control and irrigation) or for conveyancing water transport vehicles (e.g. water taxi). They carry free, calm surface ...

, and the Don–

Sea of Azov The Sea of Azov is an inland Continental shelf#Shelf seas, shelf sea in Eastern Europe connected to the Black Sea by the narrow (about ) Strait of Kerch, and sometimes regarded as a northern extension of the Black Sea. The sea is bounded by Ru ...

. A northern alternate is the Volga–Baltic (a sea which has a connection to the

of the Atlantic, as the

White Sea The White Sea (; Karelian language, Karelian and ; ) is a southern inlet of the Barents Sea located on the northwest coast of Russia. It is surrounded by Karelia to the west, the Kola Peninsula to the north, and the Kanin Peninsula to the nort ...

does via the White Sea-Baltic canal). Baku Sea Trade Port and Caspian Shipping Company CJSC, have a big role in the sea transportation of Azerbaijan. The Caspian Sea Shipping Company CJSC has two fleets plus shipyards. Its transport fleet has 51 vessels: 20 tankers, 13 ferries, 15 universal dry cargo vessels, 2 Ro-Ro vessels, as well as 1 technical vessel and 1 floating workshop. Its specialized fleet has 210 vessels: 20 cranes, 25 towing and supplying vehicles, 26 passenger, two pipe-laying, six fire-fighting, seven engineering-geological, two diving and 88 auxiliary vessels. The Caspian Sea Shipping Company of Azerbaijan, which acts as a liaison in the Transport Corridor Europe-Caucasus-Asia (TRACECA), simultaneously with the transportation of cargo and passengers in the Trans-Caspian direction, also performs work to fully ensure the processes of oil and gas production at sea. In the 19th century, the sharp increase in oil production in

gave a huge impetus to the development of shipping in the Caspian Sea, and as a result, there was a need to create fundamentally new floating facilities for the transportation of oil and oil products.

Political issues

Many of the islands along the Azerbaijani coast retain great geopolitical and economic importance for demarcation-line oil fields relying on their national status.

Bulla Island Bulla Island, also Xara Zira, Khara Zira or Khere Zire, () is an island south of the Bay of Baku, Caspian Sea. It is the largest island of the Baku Archipelago, located off Baku, Azerbaijan. Geography Bulla Island's area is ; its length is abo ...

, Pirallahı Island, and Nargin, which is still used as a former

Soviet The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...

base and is the largest island in the

bay, hold oil reserves. The collapse of the Soviet Union allowed the market opening of the region. This led to intense investment and development by international oil companies. In 1998,

Dick Cheney Richard Bruce Cheney ( ; born January 30, 1941) is an American former politician and businessman who served as the 46th vice president of the United States from 2001 to 2009 under President George W. Bush. He has been called vice presidency o ...

commented that "I can't think of a time when we've had a region emerge as suddenly to become as strategically significant as the Caspian." A key problem to further local development is arriving at precise, agreed demarcation lines among the five

states. The current disputes along Azerbaijan's maritime borders with Turkmenistan and Iran could impinge future development. Much controversy currently exists over the proposed Trans-Caspian oil and gas pipelines. These projects would allow Western markets easier access to Kazakh oil and, potentially, Uzbek and Turkmen gas as well. Russia officially opposes the project on environmental grounds.Sergei Blagov,
Russia Tries to Scuttle Proposed Trans-Caspian Pipeline
", Eurasianet (2006-03-27) However, analysts note that the pipelines would bypass Russia completely, thereby denying the country valuable transit fees, as well as destroying its current

monopoly A monopoly (from Greek language, Greek and ) is a market in which one person or company is the only supplier of a particular good or service. A monopoly is characterized by a lack of economic Competition (economics), competition to produce ...

on westward-bound

hydrocarbon In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and Hydrophobe, hydrophobic; their odor is usually fain ...

exports from the region. Recently, both Kazakhstan and Turkmenistan have expressed their support for the Trans-Caspian Pipeline. Leaked U.S. diplomatic cables revealed that BP covered up a gas leak and

blowout Blowout or Blow out may refer to: Film and television *''Blow Out'', a 1981 film by Brian De Palma * '' The Blow Out'', a 1936 short film * ''Blow Out'' (TV series), a TV series on Bravo * "Blow Out" (''Prison Break''), an episode of ''Priso ...

incident in September 2008 at an operating gas field in the Azeri-Chirag-Guneshi area of the Azerbaijan Caspian Sea.

Territorial status

Coastline

Five states are located along about of the Caspian coastline. The length of the coastline of these countries: #

– #

–

Negotiations

and the

split the Caspian sea's surface 50/50 and the sea's volume 75/25 with Iran getting more, between themselves in 1931. In 2000, negotiations as to the demarcation of the sea had been going on for nearly a decade among all the states bordering it. Whether it was by law a sea, a lake, or an agreed hybrid, the decision would set the demarcation rules and was heavily debated. Access to mineral resources (

oil An oil is any nonpolar chemical substance that is composed primarily of hydrocarbons and is hydrophobic (does not mix with water) and lipophilic (mixes with other oils). Oils are usually flammable and surface active. Most oils are unsaturate ...

and

), access for fishing, and access to

international waters The terms international waters or transboundary waters apply where any of the following types of bodies of water (or their drainage basins) transcend international boundaries: oceans, large marine ecosystems, enclosed or semi-enclosed region ...

(through Russia's

river and the canals connecting it to the

and

Baltic Sea The Baltic Sea is an arm of the Atlantic Ocean that is enclosed by the countries of Denmark, Estonia, Finland, Germany, Latvia, Lithuania, Poland, Russia, Sweden, and the North European Plain, North and Central European Plain regions. It is the ...

) all rest on the negotiations' outcome. Access to the Volga is key for market efficiency and economic diversity of the

landlocked A landlocked country is a country that has no territory connected to an ocean or whose coastlines lie solely on endorheic basins. Currently, there are 44 landlocked countries, two of them doubly landlocked (Liechtenstein and Uzbekistan), and t ...

states of Azerbaijan, Kazakhstan, and Turkmenistan. This concerns Russia as more traffic seeks to use – and at some points congest – its inland

waterway A waterway is any Navigability, navigable body of water. Broad distinctions are useful to avoid ambiguity, and disambiguation will be of varying importance depending on the nuance of the equivalent word in other ways. A first distinction is ...

s. If the body of water is, by law, a sea, many precedents and international treaties oblige free access to foreign vessels. If it is a lake there are no such obligations. Resolving and improving some

environmental Environment most often refers to: __NOTOC__ * Natural environment, referring respectively to all living and non-living things occurring naturally and the physical and biological factors along with their chemical interactions that affect an organism ...

issues properly rests on the status and

border Borders are generally defined as geography, geographical boundaries, imposed either by features such as oceans and terrain, or by polity, political entities such as governments, sovereign states, federated states, and other administrative divisio ...

s issue. All five Caspian littoral states maintain naval forces on the sea. Caspian Sea

According to a treaty signed between Iran and the Soviet Union, the sea is technically a lake and was divided into two sectors (Iranian and Soviet), but the resources (then mainly fish) were commonly shared. The line between the two sectors was considered an international border in a common lake, like Lake Albert. The Soviet sector was sub-divided into the four littoral republics' administrative sectors. Russia, Kazakhstan, and Azerbaijan have bilateral agreements with each other based on

median The median of a set of numbers is the value separating the higher half from the lower half of a Sample (statistics), data sample, a statistical population, population, or a probability distribution. For a data set, it may be thought of as the “ ...

lines. Because of their use by the three nations, median lines seem to be the most likely method of delineating territory in future agreements. However, Iran insists on a single, multilateral agreement among the five nations (aiming for a one-fifth share). Azerbaijan is at odds with Iran over some of the sea's

oil field A petroleum reservoir or oil and gas reservoir is a subsurface accumulation of hydrocarbons contained in porous or fractured rock formations. Such reservoirs form when kerogen (ancient plant matter) is created in surrounding rock by the prese ...

s. Occasionally, Iranian patrol boats have fired at vessels sent by Azerbaijan for exploration into the disputed region. There are similar tensions between Azerbaijan and Turkmenistan (the latter claims that the former has pumped more oil than agreed from a field, recognized by both parties as shared). The Caspian littoral states' meeting in 2007 signed an accord that only allows littoral-state flag-bearing ships to enter the sea. Negotiations among the five states ebbed and flowed, from about 1990 to 2018. Progress was notable in the fourth Caspian Summit held in

in 2014.

Caspian Summit

The Caspian Summit is a head of state-level meeting of the five littoral states. The fifth Caspian Summit took place on August 12, 2018, in the Kazakh port city of

. The five leaders signed the 'Convention on the Legal Status of the Caspian Sea'. Representatives of the Caspian littoral states held a meeting in the capital of Kazakhstan on September 28, 2018, as a follow-up to the Aktau Summit. The conference was hosted by the Kazakh Ministry of Investment and Development. The participants in the meeting agreed to host an investment forum for the Caspian region every two years.

Convention on the Legal Status of the Caspian Sea

The five littoral states build consensus on legally binding governance of the Caspian Sea through Special Working Groups of a Convention on the Legal Status of the Caspian Sea. In advance of a Caspian Summit, the 51st Special Working Group took place in

Astana Astana is the capital city of Kazakhstan. With a population of 1,423,726 within the city limits, it is the second-largest in the country after Almaty, which had been the capital until 1997. The city lies on the banks of the Ishim (river), Ishim ...

in May 2018 and found consensus on multiple agreements: Agreements on cooperation in the field of transport; trade and economic cooperation; prevention of incidents on the sea; combating terrorism; fighting against organized crime; and border security cooperation. The convention grants jurisdiction over of territorial waters to each neighboring country, plus an additional of exclusive fishing rights on the surface, while the rest is

. The seabed, on the other hand, remains undefined, subject to bilateral agreements between countries. Thus, the Caspian Sea is legally neither fully a sea nor a lake. While the convention addresses caviar production, oil and gas extraction, and military uses, it does not touch on environmental issues.

Crossborder inflow

UNECE The United Nations Economic Commission for Europe (ECE or UNECE) is an intergovernmental organization or a specialized body of the United Nations. The UNECE is one of five regional commissions under the jurisdiction of the United Nations Econ ...

recognizes several rivers that cross international borders which flow into the Caspian Sea. These are:

Transportation

Although the Caspian Sea is

endorheic An endorheic basin ( ; also endoreic basin and endorreic basin) is a drainage basin that normally retains water and allows no outflow to other external bodies of water (e.g. rivers and oceans); instead, the water drainage flows into permanent ...

, its main tributary, the

, is connected by important shipping canals with the Don River (and thus the Black Sea) and with the Baltic Sea, with branch canals to Northern Dvina and to the White Sea. Another Caspian tributary, the Kuma River, is connected by an irrigation canal with the Don basin as well. Scheduled

ferry A ferry is a boat or ship that transports passengers, and occasionally vehicles and cargo, across a body of water. A small passenger ferry with multiple stops, like those in Venice, Italy, is sometimes referred to as a water taxi or water bus ...

services (including

train ferries A train ferry is a ship (ferry) designed to carry railway vehicles, as well as their cargoes and passengers. Typically, one level of the ship is fitted with railway tracks, and the vessel has a door at the front and/or rear to give access to t ...

) across the sea chiefly are between: * Türkmenbaşy in

, (formerly Krasnovodsk) and

, Kazakhstan and Baku * Kuryk, Kazakhstan and Baku *Cities in Iran and Russia (chiefly for cargo.)

Canals

As an

, the Caspian Sea basin has no natural connection with the ocean. Since the

medieval period In the history of Europe, the Middle Ages or medieval period lasted approximately from the 5th to the late 15th centuries, similarly to the post-classical period of World history (field), global history. It began with the fall of the West ...

, traders reached the Caspian via a number of

portage Portage or portaging ( CA: ; ) is the practice of carrying water craft or cargo over land, either around an obstacle in a river, or between two bodies of water. A path where items are regularly carried between bodies of water is also called a '' ...

s that connected the Volga and its tributaries with the

Don River The Don () is the fifth-longest river in Europe. Flowing from Central Russia to the Sea of Azov in Southern Russia, it is one of Russia's largest rivers and played an important role for traders from the Byzantine Empire. Its basin is betwee ...

(which flows into the

) and various rivers that flow into the

. Primitive canals connecting the Volga Basin with the Baltic were constructed as early as the early 18th century. Since then, a number of canal projects have been completed. The two modern canal systems that connect the Volga Basin, and hence the Caspian Sea, with the ocean are the

Volga–Baltic Waterway The Volga–Baltic Waterway (), formerly known as the Mariinsk Canal System (), is a series of canals and rivers in Russia which link the Volga with the Baltic Sea via the Neva. Like the Volga–Don Canal, it is part of the Unified Deep Water ...

and the

Volga–Don Canal Lenin Volga–Don Shipping Canal (Russian language, Russian: Волго-Донской судоходный канал имени, ''В. И. Ленина, Volga-Donskoy sudokhodniy kanal imeni V. I. Lenina'', abbreviated ВДСК, ''VDSK'') is a ...

. The proposed

Pechora–Kama Canal The Pechora–Kama Canal (), or sometimes the Kama–Pechora Canal, was a proposed canal intended to link the basin of the Pechora River in the north of European Russia with the basin of the Kama, a tributary of the Volga. Completion of this projec ...

was a project that was widely discussed between the 1930s and 1980s. Shipping was a secondary consideration. Its main goal was to redirect some of the water of the

Pechora River The Pechora (; Komi: Печӧра; Nenets: Санэроˮ яха) is the sixth-longest river in Europe. Flowing from Northwest Russia and into the Arctic Ocean, it lies mostly in the Komi Republic but the northernmost part crosses the Nenets A ...

(which flows into the Arctic Ocean) via the

Kama River The Kama ( , ; ; ), also known as the Chulman ( ; ), is a long«Река КАМА»
Russian St ...

into the Volga. The goals were both irrigation and the stabilization of the water level in the Caspian, which was thought to be falling dangerously fast at the time. During 1971, some peaceful nuclear construction experiments were carried out in the region by the U.S.S.R. In June 2007, in order to boost his oil-rich country's access to markets,

's President

Nursultan Nazarbayev Nursultan Abishuly Nazarbayev (born 6 July 1940) is a Kazakhstani politician who served as the first president of Kazakhstan from 1991 to 2019. He also held the special title of Elbasy from 2010 to 2022 and chairman of the Security Council of ...

proposed a link between the Caspian Sea and the

. It is hoped that the "

Eurasia Canal The Eurasia Canal (, ''Kanal "Evraziya"'') is a proposed 700-kilometre-long (430 mi) canal connecting the Caspian Sea to the Black Sea along the Kuma-Manych Depression. Currently, a chain of lakes and reservoirs and the shallow irrigation K ...

" (

Manych Ship Canal The Manych Ship Canal is a canal between the Black Sea lagoon the Sea of Azov and the Caspian Sea. , proposals were being considered to turn it into a larger canal known as the Eurasia Canal. If built, this would be a multipurpose water-resourc ...

) would transform landlocked Kazakhstan and other Central Asian countries into maritime states, enabling them to significantly increase trade volume. Although the canal would traverse Russian territory, it would benefit Kazakhstan through its Caspian Sea ports. The most likely route for the canal, the officials at the Committee on Water Resources at Kazakhstan's Agriculture Ministry say, would follow the

Kuma–Manych Depression The Kuma–Manych depression () is a depression (geology), geological depression in southwestern Russia that separates the East European Plain, Russian Plain to the north from North Caucasus, Ciscaucasia to the south. It is named after the Kuma ...

, where currently a chain of rivers and lakes is already connected by an irrigation canal (the

Kuma–Manych Canal The Kuma–Manych Canal () is an irrigation canal in Russia's Stavropol Krai. The canal, completed in 1965,"Caspian Canal Could Boost Kazakh Trade"
''

Business Week ''Bloomberg Businessweek'', previously known as ''BusinessWeek'' (and before that ''Business Week'' and ''The Business Week''), is an American monthly business magazine published 12 times a year. The magazine debuted in New York City in Septembe ...

'' (2007-07-09)

References

External links

*
Names of the Caspian Sea

Caspian Sea Region

{{Authority control Caspian Sea, Ancient lakes Azerbaijan–Iran border Azerbaijan–Russia border Border tripoints Endorheic lakes of Europe Endorheic lakes of Asia Eutrophication Geography of Central Asia Geography of Europe Geography of Southern Russia Geography of West Asia International disputes International lakes of Asia International lakes of Europe Iran–Soviet Union border Iran–Turkmenistan border Kazakhstan–Russia border Kazakhstan–Turkmenistan border Lakes of Astrakhan Oblast Lakes of Azerbaijan Lakes of Dagestan Lakes of Iran Lakes of Kalmykia Lakes of Kazakhstan Lakes of Russia Lakes of Turkmenistan Landforms of Central Asia Lowest points of countries Saline lakes of Asia Saline lakes of Europe