| name | office head of government | Mayor | image | Area (m²) | date founded | Elevation (m) | Country | administrative division | continent | latitude (°) | waterbody | longitude (°) | Website | population (people) | Demonym | Map |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Körfez, Kocaeli | 356,080,000 | 50 | Turkey | Kocaeli | Asia | 40.7833328247 | Gulf of İzmit | 29.7333335876 | website | 165,503 | Map | |||||
| İzmit |  | 3,524,000,000 | 100 | Turkey | Kocaeli | Asia | 40.7666664124 | Gulf of İzmit | 29.9166660309 | website | 363,416 | Map | ||||
| Darıca |  | 24,000,000 | 50 | Turkey | Kocaeli | Asia | 40.7597236633 | Gulf of İzmit | 29.3855552673 | website | 201,468 | Map | ||||
| Derince |  | 222,970,000 | 20 | Turkey | Kocaeli | Asia | 40.7666664124 | Gulf of İzmit | 29.8166675568 | website | 140,982 | Map | ||||
| Gölcük, Kocaeli |  | 199,000,000 | 10 | Turkey | Kocaeli | Asia | 40.6666679382 | Gulf of İzmit | 29.8333339691 | website | 162,584 | Map |