Water is the defining geographical feature of Kerala, which boasts 44 rivers and a legendary backwater system.
* **Rivers:** The **Periyar River** is the state's longest, providing crucial drinking water and hydroelectric power. The **Bharathappuzha** and **Pamba** rivers also hold deep cultural and ecological significance. * **Lakes & Backwaters:** **Vembanad Lake** is the longest lake in India and the heart of the state's backwater tourism. **Ashtamudi Lake** in Kollam is another major, palm-shaped water body known for its biodiversity. * **Waterfalls:** **Athirappilly Falls**, plunging 80 feet through lush forest on the Chalakkudy River, is the largest and most famous waterfall in Kerala, often featured in Indian cinema.