İzmit, known as Nicomedia in antiquity, is a district and the capital of Kocaeli province, Turkey. It is located at the Gulf of İzmit in the Sea of Marmara, about 100 km (62 mi) east of Istanbul, on the northwestern part of Anatolia. The city center has a population of 300,611. The population of the province is 1,459,772. Unlike other provinces in Turkey, apart from Istanbul, the whole province is included within the municipality of the metropolitan center.
