Gulf of Bothnia The Gulf of Bothnia (; ; ) is divided into the Bothnian Bay and the Bothnian Sea, and it is the northernmost arm of the Baltic Sea, between Finland's west coast ( East Bothnia) and the northern part of Sweden's east coast ( West Bothnia an ...

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 ...

glacier A glacier (; or ) is a persistent body of dense ice, a form of rock, that is constantly moving downhill under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires ...

lake A lake is often a naturally occurring, relatively large and fixed body of water on or near the Earth's surface. It is localized in a basin or interconnected basins surrounded by dry land. Lakes lie completely on land and are separate from ...

tide Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon (and to a much lesser extent, the Sun) and are also caused by the Earth and Moon orbiting one another. Tide tables ...

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 ...

Bothnian Sea The Bothnian Sea (; ) links the Bothnian Bay (also called the Bay of Bothnia) with the Baltic Sea, Baltic proper. Kvarken is situated between the two. Together, the Bothnian Sea and Bay make up a larger geographical entity, the Gulf of Bothnia, ...

Vaasa Vaasa (; , ), formerly (1855-1917) known as Nikolaistad (; ),Holmöarna in Sweden. The bay is bounded by

Finland Finland, officially the Republic of Finland, is a Nordic country in Northern Europe. It borders Sweden to the northwest, Norway to the north, and Russia to the east, with the Gulf of Bothnia to the west and the Gulf of Finland to the south, ...

to the east and

Sweden Sweden, formally the Kingdom of Sweden, is a Nordic countries, Nordic country located on the Scandinavian Peninsula in Northern Europe. It borders Norway to the west and north, and Finland to the east. At , Sweden is the largest Nordic count ...

to the west. The bay is asymmetric, with a smoother and shallower bottom slope on the Finnish side, and a deeper bottom with a steeper and more rugged coast on the Swedish side. The Bothnian Bay has a catchment area of . Of this, 56% lies in Finland, 44% in Sweden and less than 1% in Norway. The catchment contains about of forest, split roughly equally between Sweden and Finland. The average depth is . The Luleå Deep is the deepest part of the bay, at , southeast of the town of

Luleå Luleå ( , , locally ; ; ) is a Cities in Sweden, city on the coast of northern Sweden, and the County Administrative Boards of Sweden, capital of Norrbotten County, the northernmost county in Sweden. Luleå has 48,728 inhabitants in its urban ...

. On the Finnish side the average depth is . The deepest part is near the island of

Lönkytin Lönkytin is an island in the Finland, Finnish sector of the Bay of Bothnia, off shore from the town of Haukipudas. Description Lönkytin is a high, rocky islet. It is located about west-northwest of the mouth of the Kiiminkijoki river, to the ...

, with a depth of . File:Bottenviken.png, Map of the Gulf of Bothnia showing location of Bothnian Bay (shaded and labelled Bottenviken) File:Bothnian Bay map-fi.png, Finnish map of the bay – click to enlarge File:Scandinavia M2002074 lrg.jpg, Satellite image of

Fennoscandia __NOTOC__ Fennoscandia (Finnish language, Finnish, Swedish language, Swedish and ; ), or the Fennoscandian Peninsula, is a peninsula in Europe which includes the Scandinavian Peninsula, Scandinavian and Kola Peninsula, Kola peninsulas, mainland ...

with

sea ice Sea ice arises as seawater freezes. Because ice is less density, dense than water, it floats on the ocean's surface (as does fresh water ice). Sea ice covers about 7% of the Earth's surface and about 12% of the world's oceans. Much of the world' ...

covering the Bothnian Bay (white region in center)

Isostatic rebound

The bay lies in the area in Northern Europe where the ice was at its thickest during the last ice age. The Bay of Bothnia was under ice until the "

Ancylus Lake Ancylus Lake is a name given by geologists to a large freshwater lake that existed in northern Europe approximately from 8,750 to 7,850 years Before Christ, BC, being in effect one of various predecessors to the modern Baltic Sea. Origin, evoluti ...

" period (7500–6000 BC), when the ice sheet withdrew to the mountains of Northern Scandinavia. The land is now rising by

post-glacial rebound Post-glacial rebound (also called isostatic rebound or crustal rebound) is the rise of land masses after the removal of the huge weight of ice sheets during the last glacial period, which had caused isostatic depression. Post-glacial rebound an ...

at the highest rate in the Baltic Sea, at an estimated rate of a year. Today the Bothnian Bay lies around higher than it did at the end of the Last Ice Age. The local population has seen the sea retreating during their lifetimes from piers and boathouses, leaving them stranded on land. Some former islands such as Porsön and Hertsön near the city of

Luleå Luleå ( , , locally ; ; ) is a Cities in Sweden, city on the coast of northern Sweden, and the County Administrative Boards of Sweden, capital of Norrbotten County, the northernmost county in Sweden. Luleå has 48,728 inhabitants in its urban ...

are still called islands, but are now connected to the mainland. The maximum depth at the Kvarken sound today is around . Within 2,000 years, the exit from the bay at Kvarken will be raised above sea level, which will result in it becoming Europe's largest lake.

Hydrology

The Bothnian Bay has a harsher environment than other parts of the greater Baltic Sea. The bay is ice-covered for 110 to 190 days each year. Tides have little effect, but high winds driving the water from the south or north may cause the water level to rise or fall by . Major rivers that flow into the bay include: The salinity is only about 0.2 psu in the northern part of the bay, dropping almost to zero in some of the archipelagos with large river inflows. The low salinity and cold temperatures in winter results in ice that is considerably stronger than more saline or warmer ice.

Islands

If an

island An island or isle is a piece of land, distinct from a continent, completely surrounded by water. There are continental islands, which were formed by being split from a continent by plate tectonics, and oceanic islands, which have never been ...

is defined as an area of land more than that is surrounded by water, the Bay of Bothnia has 4,001 islands. The largest island is Hailuoto. The north of the bay contains a large archipelago area. The Swedish portion of this area is the Norrbotten archipelago. This is divided into the

Piteå Piteå (; ) is a locality and the seat of Piteå Municipality in Norrbotten County, Sweden. Piteå is Sweden's 58th largest city, with a population of 23,326. Geography Piteå is located at the mouth of the Pite River (), at the shore of ...

,

Luleå Luleå ( , , locally ; ; ) is a Cities in Sweden, city on the coast of northern Sweden, and the County Administrative Boards of Sweden, capital of Norrbotten County, the northernmost county in Sweden. Luleå has 48,728 inhabitants in its urban ...

, Kalix and

Haparanda Haparanda (; Meänkieli and Finnish: ''Haaparanta'', ) is a locality and the seat of Haparanda Municipality in Norrbotten County, Sweden. It is adjacent to Tornio, Finland. Haparanda has a population of 9,166 inhabitants (2024). Haparanda is ...

archipelagos. Many of the islands are uninhabited and in a natural state. In the winter the larger islands may be accessed via ice roads. Some of them are inhabited or have seasonal fishing villages used by people from the mainland. The Swedish Haparanda Archipelago National Park () occupies the Haparanda group of islands, bordering the Finnish Bothnian Bay National Park. It includes the larger islands of Sandskär and Seskar Furö, and some smaller islands and skerries. All of these islands have emerged in the last 1,500 years as the bed of the bay has risen. The Bay of Bothnia National Park in the Finnish section (, ), established in 1991, is located in the archipelago offshore from

Tornio Tornio (; ; ; ) is a city and municipalities of Finland, municipality in Lapland, Finland. The city forms a cross-border Twin cities, twin city together with Haparanda on the Swedish side. The municipality covers an area of , of which is wat ...

and

Kemi Kemi (; ; ; ) is a cities of Finland, town and municipalities of Finland, municipality of Finland. It is located approximately from the city of Tornio and the Finland–Sweden border, Swedish border. The distance to Oulu is to the south and t ...

. It covers of which about is land.

Climate

The immediate coastal areas of the Bothnian Bay tend to be bordering between humid continental and

subarctic The subarctic zone is a region in the Northern Hemisphere immediately south of the true Arctic, north of hemiboreal regions and covering much of Alaska, Canada, Iceland, the north of Fennoscandia, Northwestern Russia, Siberia, and the Cair ...

climates. The summers on the coastlines are the northernmost coastlines to average above in summer. In winter the sea freezes over, many times completely. This means that there is vast

seasonal lag Seasonal lag is the phenomenon whereby the date of maximum average air temperature at a geographical location on a planet is delayed until some time after the date of maximum daylight (i.e. the summer solstice). This also applies to the minimum ...

offshore such as on the island of Rödkallen on the Swedish side. Due to the mild nature of summers and the low diurnals, offshore islands tend to be humid continental since September usually stays above means.

Ecology

The Quark ridge at the south of the bay defines the dividing line beyond which many salt water species are unable to survive. Instead of the red and brown algae found further south, the bay has predominantly

green algae The green algae (: green alga) are a group of chlorophyll-containing autotrophic eukaryotes consisting of the phylum Prasinodermophyta and its unnamed sister group that contains the Chlorophyta and Charophyta/ Streptophyta. The land plants ...

and phanerogams. Annual plant species are almost completely dominant. The only perennials are a few specimens of the freshwater cryptogam '' Isoetes echinospora'' and the moss '' Fontinalis dalecarlica''. Often the green algae have a dense covering of epiphytic diatoms. The shores, beaches and shallows include a variety of northern plant species including the endemic yellow hair grass ('' Deschampsia bottnica''). The only filter feeders are '' Ephydatia'' and, at the river mouths, small numbers of freshwater mussels. Bivalves make up 9% of animal biomass. Crustaceans, mostly '' Saduria entomon'' make up 45% and

gastropoda Gastropods (), commonly known as slugs and snails, belong to a large Taxonomy (biology), taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, freshwater, and fro ...

30%. The gastropoda are grazing snails related to freshwater species. Fish species found in the area's lakes and rivers also live in the bay, including roach, perch, pike and grayling. Ringed seal, grey seal,

cod Cod (: cod) is the common name for the demersal fish genus ''Gadus'', belonging to the family (biology), family Gadidae. Cod is also used as part of the common name for a number of other fish species, and one species that belongs to genus ''Gad ...

,

herring Herring are various species of forage fish, belonging to the Order (biology), order Clupeiformes. Herring often move in large Shoaling and schooling, schools around fishing banks and near the coast, found particularly in shallow, temperate wate ...

and

salmon Salmon (; : salmon) are any of several list of commercially important fish species, commercially important species of euryhaline ray-finned fish from the genera ''Salmo'' and ''Oncorhynchus'' of the family (biology), family Salmonidae, native ...

may also be found in the bay. In the 16th century seals were hunted in the Bay of Bothnia. Ringed seals were captured using nets in the inshore open water, and were stalked and captured in their dens or at breathing holes. Both grey and ringed seals were hunted along the edge of the ice. Wild vendace

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 ...

harvested from the Kalix River, known as ''Kalix Löjrom'' or as sea gold, is a delicacy with a European

protected designation of origin The protected designation of origin (PDO) is a type of geographical indication of the European Union aimed at preserving the designations of origin of food-related products. The designation was created in 1992 and its main purpose is to designat ...

. Birdlife includes the

black guillemot The black guillemot or tystie (''Cepphus grylle'') is a medium-sized seabird of the Alcidae family, native throughout northern Atlantic coasts and eastern North American coasts. It is resident in much of its range, but large populations from the ...

, velvet scoter,

oystercatcher The oystercatchers are a group of waders forming the family (biology), family Haematopodidae, which has a single genus, ''Haematopus''. They are found on coasts worldwide apart from the polar regions and some tropical regions of Africa and Sout ...

, lesser black-backed gull, western capercaillie and

willow ptarmigan The willow ptarmigan ( ); ''Lagopus lagopus'') or willow grouse is a bird in the grouse subfamily Tetraoninae of the pheasant family Phasianidae. It is also known colloquially as awebo bird. The willow ptarmigan breeds in birch and other forests ...

. Moose and hare are found on the islands, as on the mainland. Occasionally, whales have been observed in the

Bothnian Sea The Bothnian Sea (; ) links the Bothnian Bay (also called the Bay of Bothnia) with the Baltic Sea, Baltic proper. Kvarken is situated between the two. Together, the Bothnian Sea and Bay make up a larger geographical entity, the Gulf of Bothnia, ...

and remains of extinct Atlantic

gray whale The gray whale (''Eschrichtius robustus''), also known as the grey whale,Britannica Micro.: v. IV, p. 693. is a baleen whale that migrates between feeding and breeding grounds yearly. It reaches a length of , a weight of up to and lives between ...

was found from GräsöJones L.M..Swartz L.S.. Leatherwood S.
The Gray Whale: Eschrichtius Robustus
"Eastern Atlantic Specimens". pp 41-44.

Academic Press Academic Press (AP) is an academic book publisher founded in 1941. It launched a British division in the 1950s. Academic Press was acquired by Harcourt, Brace & World in 1969. Reed Elsevier said in 2000 it would buy Harcourt, a deal complete ...

. Retrieved on September 05, 2017 while it is not clear whether or not whales might once have reached Bothnian Bay historically.

Population

Ports on the Finnish side include Haukipudas,

Jakobstad Jakobstad (; , ) is a town in Finland, located on the west coast of the country. Jakobstad is situated in Ostrobothnia (administrative region), Ostrobothnia, along the Gulf of Bothnia. The population of Jakobstad is approximately , while the Jako ...

,

Kemi Kemi (; ; ; ) is a cities of Finland, town and municipalities of Finland, municipality of Finland. It is located approximately from the city of Tornio and the Finland–Sweden border, Swedish border. The distance to Oulu is to the south and t ...

,

Kokkola Kokkola (; , ) is a town in Finland and the regional capital of Central Ostrobothnia. It is located on the west coast of the country, on the Gulf of Bothnia. The population of Kokkola is approximately , while the Kokkola sub-region, sub-region h ...

,

Oulu Oulu ( , ; ) is a city in Finland and the regional capital of North Ostrobothnia. It is located on the northwestern coast of the country at the mouth of the Oulujoki, River Oulu. The population of Oulu is approximately , while the Oulu sub-regio ...

, Raahe and

Tornio Tornio (; ; ; ) is a city and municipalities of Finland, municipality in Lapland, Finland. The city forms a cross-border Twin cities, twin city together with Haparanda on the Swedish side. The municipality covers an area of , of which is wat ...

. The largest towns by population on the Finnish side as of 2013 were

Oulu Oulu ( , ; ) is a city in Finland and the regional capital of North Ostrobothnia. It is located on the northwestern coast of the country at the mouth of the Oulujoki, River Oulu. The population of Oulu is approximately , while the Oulu sub-regio ...

(192,680),

Tornio Tornio (; ; ; ) is a city and municipalities of Finland, municipality in Lapland, Finland. The city forms a cross-border Twin cities, twin city together with Haparanda on the Swedish side. The municipality covers an area of , of which is wat ...

(22,374),

Kemi Kemi (; ; ; ) is a cities of Finland, town and municipalities of Finland, municipality of Finland. It is located approximately from the city of Tornio and the Finland–Sweden border, Swedish border. The distance to Oulu is to the south and t ...

(22,157),

Kempele Kempele is a municipality south of the city of Oulu and south of the Oulu Airport in Northern Finland. Historically it was in the Provinces of Finland, province of Oulu (province), Oulu, but today it is in the region of North Ostrobothnia. The p ...

(16,549), Raahe (25,641), Kalajoki (12,637),

Kokkola Kokkola (; , ) is a town in Finland and the regional capital of Central Ostrobothnia. It is located on the west coast of the country, on the Gulf of Bothnia. The population of Kokkola is approximately , while the Kokkola sub-region, sub-region h ...

(46,697) and

Jakobstad Jakobstad (; , ) is a town in Finland, located on the west coast of the country. Jakobstad is situated in Ostrobothnia (administrative region), Ostrobothnia, along the Gulf of Bothnia. The population of Jakobstad is approximately , while the Jako ...

(19,636). In Finland the catchment area included about of arable land as of 1993. There were four Finnish pulp and paper mills, of which two (Veitsiluoto Oy and Metsä Botnia Oy) were producing bleached kraft paper. On the Swedish side ports include

Haparanda Haparanda (; Meänkieli and Finnish: ''Haaparanta'', ) is a locality and the seat of Haparanda Municipality in Norrbotten County, Sweden. It is adjacent to Tornio, Finland. Haparanda has a population of 9,166 inhabitants (2024). Haparanda is ...

, Karlsborg, Kalix,

Luleå Luleå ( , , locally ; ; ) is a Cities in Sweden, city on the coast of northern Sweden, and the County Administrative Boards of Sweden, capital of Norrbotten County, the northernmost county in Sweden. Luleå has 48,728 inhabitants in its urban ...

,

Piteå Piteå (; ) is a locality and the seat of Piteå Municipality in Norrbotten County, Sweden. Piteå is Sweden's 58th largest city, with a population of 23,326. Geography Piteå is located at the mouth of the Pite River (), at the shore of ...

and

Skellefteå Skellefteå (, locally ) is a Cities in Sweden, city in Västerbotten County, Sweden, with a population of 36,388. It is the seat of Skellefteå Municipality, which had 77,322 inhabitants in 2024. The city is historically industrial, with mining ...

. The largest towns on the Swedish side as of 2013 were Luleå (74,000), Skellefteå (71,641), Piteå (40,860) and Kalix (16,926). Luleå is the largest city in

Norrbotten Norrbotten (), sometimes called North Bothnia, is a Swedish province (''landskap'') in northernmost Sweden. It borders south to Västerbotten, west to Swedish Lapland, and east to Finland. Administration The traditional provinces of Swede ...

, with the largest airport. The 1,312 islands of the Luleå archipelago are an important tourist attraction, as is the Gammelstad church village, listed as a Unesco World Heritage site. As of 1993 there were about of arable land in the Swedish part of the catchment basin, mostly used for small-scale low-intensity farming. There were five pulp and paper mills, of which one produced bleached kraft paper. In the late 1960s the bay was being used to transport fuel oil to the Finnish settlements around the bay. In 1968 about 950,000 tons of cellulose and 230,600 tons of paper and cardboard were exported, a figure that was rising. In 1968 ships calling at the Finnish ports carried about 388,872 tons of iron bars and 64,326 tons of steel sheets. Mining and mineral products such as coal and ore were carried to and from the ports, and steel products were exported. Sea transport continued throughout the winter. In 1993 there were two non-ferrous heavy metal smelters, in Rönnskär and Kokkola, emitting significant quantities of heavy metals. Efforts were being made to reduce emissions. The

drainage basin A drainage basin is an area of land in which all flowing surface water converges to a single point, such as a river mouth, or flows into another body of water, such as a lake or ocean. A basin is separated from adjacent basins by a perimeter, ...

also held three iron and steel plants and a number of mines. Human activities have affected the fragile sub-arctic environment. Dredging and other activities related to sea transport affect marine life. Agriculture, forestry and peat mining in the catchment basin add nutrients to the bay, affecting the ecological balance, while pollutants are delivered from steel mills and from pulp and paper mills around the bay, as well as from sewage treatment plants. Steel mills and stainless steel plants may have released

nickel Nickel is a chemical element; it has symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive, but large pieces are slo ...

and

chromium Chromium is a chemical element; it has Symbol (chemistry), symbol Cr and atomic number 24. It is the first element in Group 6 element, group 6. It is a steely-grey, Luster (mineralogy), lustrous, hard, and brittle transition metal. Chromium ...

. Efforts have been made to reduce pollution through improved technology, but some areas along the Finnish coastline show evidence of

eutrophication Eutrophication is a general term describing a process in which nutrients accumulate in a body of water, resulting in an increased growth of organisms that may deplete the oxygen in the water; ie. the process of too many plants growing on the s ...

. Compared to other parts of the Baltic, higher levels of nitrate have been found in the Bothnian Bay and lower levels of phosphate and silicates.

Gallery

File:Seskaro bridge.jpg, The bridge to Seskarö, Sweden File:Icebreaker Fennica.jpg, Finnish icebreaker MSV ''Fennica'' in the Bay File:SampoIceTrac.JPG, Looking back from the Icebreaker Sampo near

Kemi Kemi (; ; ; ) is a cities of Finland, town and municipalities of Finland, municipality of Finland. It is located approximately from the city of Tornio and the Finland–Sweden border, Swedish border. The distance to Oulu is to the south and t ...

, Finland File:Outokumpu mill in Tornio 20121015.jpg, Outokumpu mill in

Tornio Tornio (; ; ; ) is a city and municipalities of Finland, municipality in Lapland, Finland. The city forms a cross-border Twin cities, twin city together with Haparanda on the Swedish side. The municipality covers an area of , of which is wat ...

File:Oulu Toppila.jpg, Old mill buildings and harbour in Toppila, Oulu, Finland File:20080227 Varessäikkä Siikajoki.jpg, Buildings and the birdwatching tower at Varessäikkä harbour, Siikajoki, Finland File:Mökki Pallosessa.jpg, Old fisherman's cottage File:Lönkytin.jpg,

Lönkytin Lönkytin is an island in the Finland, Finnish sector of the Bay of Bothnia, off shore from the town of Haukipudas. Description Lönkytin is a high, rocky islet. It is located about west-northwest of the mouth of the Kiiminkijoki river, to the ...

island File:Kahvankari Oulu.jpg, The island of Kahvankari in

Oulu Oulu ( , ; ) is a city in Finland and the regional capital of North Ostrobothnia. It is located on the northwestern coast of the country at the mouth of the Oulujoki, River Oulu. The population of Oulu is approximately , while the Oulu sub-regio ...

, Finland File:Kraaseli in Kello.JPG, The eastern shore of the Kellon Kraaseli island, Haukipudas, Finland File:Bothnian Bay Kemi.jpg, Bothnian Bay in

Kemi Kemi (; ; ; ) is a cities of Finland, town and municipalities of Finland, municipality of Finland. It is located approximately from the city of Tornio and the Finland–Sweden border, Swedish border. The distance to Oulu is to the south and t ...

, Finland File:Auringonlasku.jpg, Sunset at Hiekkasärkät, Kalajoki, Finland

References

Citations Sources * * * * * * * * * * * * * * * * * * * * * * {{List of seas Gulf of Bothnia Landforms of Norrbotten County Landforms of Västerbotten County

Extent

Isostatic rebound

Hydrology

Islands

Climate

Ecology

Population

Gallery

References