Geography

The peninsula is at the north west corner of Anatolia

Anatolia

Anatolia is a geographic and historical term denoting the westernmost protrusion of Asia, comprising the majority of the Republic of Turkey...

. The length toward west is 90 kilometres (55.9 mi) and the average width is about 40 kilometres (24.9 mi). It is bordered by the Black Sea

Black Sea

The Black Sea is bounded by Europe, Anatolia and the Caucasus and is ultimately connected to the Atlantic Ocean via the Mediterranean and the Aegean seas and various straits. The Bosphorus strait connects it to the Sea of Marmara, and the strait of the Dardanelles connects that sea to the Aegean...

 to the north, Sea of Marmara

Sea of Marmara

The Sea of Marmara , also known as the Sea of Marmora or the Marmara Sea, and in the context of classical antiquity as the Propontis , is the inland sea that connects the Black Sea to the Aegean Sea, thus separating Turkey's Asian and European parts. The Bosphorus strait connects it to the Black...

 to the south and the strait of Bosphorus  to the west. The geographers consider it to be a part of Kocaeli Çatalca subregion, where Çatalça

Çatalca Peninsula

-Geography:The peninsula is roughly rectangular. It is bordered by the Black Sea to the north, Sea of Marmara to the South and Bosphorus to the east. The west border is more or less arbitrary. But usually the western border of İstanbul Province is also taken as the border of the peninsula . With...

 is a peninsula on the other side of Bosphorous. .

History

Together with the strait of Dardanelles

Dardanelles

The Dardanelles , formerly known as the Hellespont, is a narrow strait in northwestern Turkey connecting the Aegean Sea to the Sea of Marmara. It is one of the Turkish Straits, along with its counterpart the Bosphorus. It is located at approximately...

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

Europe

Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

 to Asia

Asia

Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...

 and vice versa. During ancient times, Phryigians

Phrygia

In antiquity, Phrygia was a kingdom in the west central part of Anatolia, in what is now modern-day Turkey. The Phrygians initially lived in the southern Balkans; according to Herodotus, under the name of Bryges , changing it to Phruges after their final migration to Anatolia, via the...

, Bithynians

Bithynia

Bithynia was an ancient region, kingdom and Roman province in the northwest of Asia Minor, adjoining the Propontis, the Thracian Bosporus and the Euxine .-Description:...

 and Galatians were some of them. But while Phryigians and Galatians moved to Central Anatolia, it was the Bithinians who controlled the region for a considerable time. Hannibal, the Carthaginian commander who took refuge in Bithinia died in Kocaeli Peninsula at around 182 BC. His grave may be around Dilovası

Dilovası

Dilovası is a town and district of Kocaeli Province in the Marmara region of Turkey. It was ceded from Gebze district in 2008. The mayor is Cemil Yaman .- External links :*...

 or at Gebze

Gebze

Gebze is an industrial city in Kocaeli Province, Turkey. Situated 30 miles east of Istanbul on the northern shore of the Sea of Marmara, it is the largest district of Kocaeli; Gebze has experienced rapid growth in recent years- from 159,116 in 1990, to 282,444 in 2009. Gebze accounts for 15% of...

 both at about the middle of Kocaeli Peninsula. Later the peninsula was a part of the Roman Empire

Roman Empire

The Roman Empire was the post-Republican period of the ancient Roman civilization, characterised by an autocratic form of government and large territorial holdings in Europe and around the Mediterranean....

, the Byzantine Empire

Byzantine Empire

The Byzantine Empire was the Eastern Roman Empire during the periods of Late Antiquity and the Middle Ages, centred on the capital of Constantinople. Known simply as the Roman Empire or Romania to its inhabitants and neighbours, the Empire was the direct continuation of the Ancient Roman State...

, and the Ottoman Empire

Ottoman Empire

The Ottoman EmpireIt was usually referred to as the "Ottoman Empire", the "Turkish Empire", the "Ottoman Caliphate" or more commonly "Turkey" by its contemporaries...

.

The population and the economy

Kocaeli Peninsula is one of the most industrialised regions of Turkey. Approximatelly one third of İstanbul

Istanbul

Istanbul , historically known as Byzantium and Constantinople , is the largest city of Turkey. Istanbul metropolitan province had 13.26 million people living in it as of December, 2010, which is 18% of Turkey's population and the 3rd largest metropolitan area in Europe after London and...

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

Izmit

İzmit is a city in Turkey, administrative center of Kocaeli Province as well as the Kocaeli Metropolitan Municipality. It is located at the Gulf of İzmit in the Sea of Marmara, about east of Istanbul, on the northwestern part of Anatolia. The city center has a population of 294.875...

another big city is at the east most point of the peninsula. The southern coastline (Marmara) between the two is full of settlements, factories and the shipyards. The population density along this coastline is very high. But the population density along the northern (Black Sea) coastline is low.