Gölcük, Kocaeli

Gölcük
Map showing Gölcük District in Kocaeli Province
Gölcük
Location in Turkey
Gölcük
Gölcük (Marmara)
Coordinates: 40°43′02″N 29°49′22″E / 40.71722°N 29.82278°E / 40.71722; 29.82278
CountryTurkey
ProvinceKocaeli
Government
  MayorAli Yıldırım Sezer (AKP)
Area
217 km2 (84 sq mi)
Population
 (2022)
175,940
  Density810/km2 (2,100/sq mi)
Time zoneUTC+3 (TRT)
Postal code
41650
Area code0262
Websitewww.golcuk.bel.trğ

Gölcük, historically known as Diolkides, is a municipality and district of Kocaeli Province, Turkey. Its area is 217 km2, and its population is 175,940 (2022). Gölcük is located on the southern shore of the Gulf of İzmit, which is the easternmost inlet of the Sea of Marmara.

Gölcük is home to the Gölcük Naval Base and Gölcük Naval Shipyard of the Turkish Navy. A Ford Otosan automobile plant is also located in the district.