The Kocaeli Peninsula () lies in the northwest corner of

Anatolia Anatolia (), also known as Asia Minor, is a peninsula in West Asia that makes up the majority of the land area of Turkey. It is the westernmost protrusion of Asia and is geographically bounded by the Mediterranean Sea to the south, the Aegean ...

Turkey Turkey, officially the Republic of Türkiye, is a country mainly located in Anatolia in West Asia, with a relatively small part called East Thrace in Southeast Europe. It borders the Black Sea to the north; Georgia (country), Georgia, Armen ...

, separating 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 ...

and the

Sea of Marmara The Sea of Marmara, also known as the Sea of Marmora or the Marmara Sea, is a small inland sea entirely within the borders of Turkey. It links the Black Sea and the Aegean Sea via the Bosporus and Dardanelles straits, separating Turkey's E ...

on the Asian side of the strait of

Bosphorus The Bosporus or Bosphorus Strait ( ; , colloquially ) is a natural strait and an internationally significant waterway located in Istanbul, Turkey. The Bosporus connects the Black Sea to the Sea of Marmara and forms one of the continental bo ...

. Approximately one-third of

Istanbul Istanbul is the List of largest cities and towns in Turkey, largest city in Turkey, constituting the country's economic, cultural, and historical heart. With Demographics of Istanbul, a population over , it is home to 18% of the Demographics ...

, one of the most populous cities of the world, occupies its western part, and

İzmit İzmit () is a municipality and the capital Districts of Turkey, district of Kocaeli Province, Turkey. Its area is 480 km2, and its population is 376,056 (2022). The capital of Kocaeli Province, it is located at the Gulf of İzmit in the Sea ...

, another big city, is at the easternmost point of the peninsula.

Geography

The peninsula is at the north west corner of

. The length toward west is and the average width is about . It is bordered by the

to the north,

to the south and the strait of

() to the west. The geographers consider it to be a part of Kocaeli Çatalca subregion, where

Çatalca Çatalca () is a municipality and Districts of Turkey, district of Istanbul Province, Istanbul Province, Turkey. Its area is 1142 km2, making it the largest district in Istanbul Province by area. Its population is 77,468 (2022). It is in Eas ...

is a peninsula on the other side of Bosphorous.

History

Together with the strait of

Dardanelles The Dardanelles ( ; ; ), also known as the Strait of Gallipoli (after the Gallipoli peninsula) and in classical antiquity as the Hellespont ( ; ), is a narrow, natural strait and internationally significant waterway in northwestern Turkey th ...

, the passage through Bosphorus and the Kocaeli peninsula is the main passage of people from

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 ...

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 ...

. During ancient times,

Phrygia In classical antiquity, Phrygia ( ; , ''Phrygía'') was a kingdom in the west-central part of Anatolia, in what is now Asian Turkey, centered on the Sangarios River. Stories of the heroic age of Greek mythology tell of several legendary Ph ...

ns,

Bithynia Bithynia (; ) was an ancient region, kingdom and Roman province in the northwest of Asia Minor (present-day Turkey), adjoining the Sea of Marmara, the Bosporus, and the Black Sea. It bordered Mysia to the southwest, Paphlagonia to the northeast a ...

ns and Galatians were some of them. But while Phrygians and Galatians moved to Central Anatolia, it was the Bithynians who controlled the region for a considerable time.

Hannibal Hannibal (; ; 247 – between 183 and 181 BC) was a Punic people, Carthaginian general and statesman who commanded the forces of Ancient Carthage, Carthage in their battle against the Roman Republic during the Second Punic War. Hannibal's fat ...

, the Carthaginian commander who took refuge in Bithynia, died in Kocaeli Peninsula at around 182 BC. His grave may be around Dilovası or at Gebze both at about the middle of Kocaeli Peninsula. Later the peninsula was a part of the

Roman Empire The Roman Empire ruled the Mediterranean and much of Europe, Western Asia and North Africa. The Roman people, Romans conquered most of this during the Roman Republic, Republic, and it was ruled by emperors following Octavian's assumption of ...

, the

Byzantine Empire The Byzantine Empire, also known as the Eastern Roman Empire, was the continuation of the Roman Empire centred on Constantinople during late antiquity and the Middle Ages. Having survived History of the Roman Empire, the events that caused the ...

, and the

Ottoman Empire The Ottoman Empire (), also called the Turkish Empire, was an empire, imperial realm that controlled much of Southeast Europe, West Asia, and North Africa from the 14th to early 20th centuries; it also controlled parts of southeastern Centr ...

. In Byzantine times and among the local Greek population until the early 20th century, the peninsula was known as Mesothynia (Μεσοθυνία, "Middle Thynia").

Population and economy

Kocaeli Peninsula is one of the most industrialised regions of Turkey. Approximately one-third of

, one of the most populous cities of the world, lies on the westernmost point of the Kocaeli peninsula, and

, another big city, is at the easternmost point of the peninsula. The southern coastline (Marmara) between the two is dotted with settlements, factories and the shipyards. Population density along this coastline is very high, as opposed to the northern (Black Sea) coastline.Geography portal
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References

{{coord, 41, 00, N, 29, 36, E, type:landmark_source:kolossus-frwiki, display=title Marmara region Peninsulas of Turkey Landforms of Istanbul Province Landforms of Kocaeli Province