Vembanad (Malayalam: [ʋeːmbɐnaːɖə̆]) is the longest lake in India, and the largest in the state of Kerala. The lake has an area of 2,033 square kilometers and a maximum length of 96.5 km.

Spanning three districts in the state of Kerala, it is known as Vembanad Lake in Kottayam, Vaikom, Changanassery, Punnamada Lake in Alappuzha, Punnappra, Kuttanadu and Kochi Lake in Kochi. Several groups of small islands including Vypin, Mulavukad, Maradu, Udayamperoor, Vallarpadam, and Willingdon Island are located in the Kochi Lake portion. Kochi Port is built around Willingdon Island and Vallarpadam island.

Kuttanad, also known as The Rice Bowl of Kerala, has the lowest altitude in India, and is also one of the few places in world where cultivation takes place below sea level. Kuttanad lies on the southern portion of Vembanad. The Nehru Trophy Boat Race is conducted in a portion of the lake. High levels of pollution have been noticed at certain hotspots of the Vembanad backwaters. The Government of India has identified the Vembanad wetland under the National Wetlands Conservation Programme.