Gulf of İzmit
Gulf of İzmit (Turkish: İzmit Körfezi), anciently, Sinus Astacenus and Olbianus Sinus (Ancient Greek: Ὀλβιανὸς κόλπος, romanized: Olbianos kolpos), also referred to as Izmit Bay, is a bay at the easternmost edge of the Sea of Marmara, in Kocaeli Province, Turkey. In antiquity it was known first as the Gulf of Astacus and later as the Gulf of Nicomedia.
The gulf takes its name from the city of İzmit, other cities and towns around the bay being Gebze, Körfez, Gölcük, and Altınova. In the east–west direction, it extends for a length of about 48 kilometres (30 mi), while in the north–south direction its width varies from 2 to 3 kilometres (1.2 to 1.9 mi) at the narrowest spots to about 10 kilometres (6.2 mi) at its widest. The İzmit Bay Bridge is a suspension bridge that bridges the gulf.