Jaffna's geography is defined by the water that surrounds and intersects it.
- **Lagoons**: The peninsula is nearly surrounded by water, most notably the **Jaffna Lagoon**, **Vadamarachchi Lagoon**, and **Elephant Pass Lagoon**. - **The Palk Strait**: This narrow strip of the Indian Ocean separates Jaffna from southern India and is central to the local fishing industry. - **Underground Aquifers**: With no major freshwater rivers, Jaffna relies heavily on underground karst limestone aquifers for fresh water. The **Nilavarai bottomless well** is a famous, seemingly inexhaustible natural limestone sinkhole that provides fresh water.