Colombo's geography and history are deeply defined by water, offering trade, sustenance, and natural beauty.
* **Indian Ocean:** The city's entire western border is the coastline of the Laccadive Sea (Indian Ocean), providing its vital shipping port and scenic waterfront promenades like Galle Face Green. * **Rivers & Lakes:** The **Kelani River** flows along the city's northern boundary, historically crucial for trade and transport. Inland, the serene **Beira Lake** dominates the central geography, while the **Diyawanna Oya** (a sprawling lake system surrounding the Sri Lankan Parliament complex in adjacent Sri Jayawardenepura Kotte) provides a lush, aquatic landscape.