Located on the western coast of Sri Lanka, Colombo sits adjacent to the country's administrative capital, Sri Jayawardenepura Kotte. The city's geography is fundamentally shaped by water. To the west, it borders the warm waters of the Indian Ocean. To the north, the Kelani River—one of Sri Lanka's major waterways—flows into the sea, forming a natural boundary.
A defining geographical feature of the inner city is Beira Lake. Once a massive, sprawling body of water used by the Portuguese and Dutch for defense and transport, it has since been contained but remains a central landmark, dividing various commercial and residential districts. The city also features a network of historic canals that once served as crucial transport arteries.
While highly urbanized, Colombo is punctuated by several large green spaces and wetlands. The coastal nature of the city means it is subject to the maritime influences of the Indian Ocean, which dictates its weather patterns and provides a vital economic resource through the Port of Colombo.