Izmit (Ĭzmēt´) or Kocaeli (kō´jäĕl´ē), city (1990 pop. 254,768), capital of Kocaeli prov., NW Turkey, on the Bay of Izmit, at the eastern end of the Sea of Marmara. A port, it is the center of a rich tobacco- and olive-growing region. Manufactures include paper, petrochemicals, textiles, beer, and cement. Founded c.712 BC, it was rebuilt in 264 BC by Nicomedus I of Bithynia, who made it his capital, Nicomedia. It was shattered by an earthquake in 1999.