One of the largest lakes in India, the Vembanad Lake is India's longest lake and also the largest lake in all of Kerala. The districts of Allepey, Kottayam and Ernakulam border the lake. A distinctive feature of the lake is that it has been divided into two parts by the Thannermukkom salt water barrier, which leaves one part of the lake with brackish water perennially and the second part with fresh water from the rivers draining into the lake.
The Vembanad Lake is at the centre of Kerala Backwaters tourism with a myriad ketuvallams (houseboats) crowding it. There are several other reasons which attract tourists to the beautiful lake, in and off season. The town of Allepey, bordering the lake, is considered to be the Venice of the East because of the large network of canals that amble through the town. Also, the Vallam Kali (the Snake Boat Race) held annually in August is a major attraction. The Kumarakom Bird Sanctuary is located on the east coast of the lake and never fails to draw a huge and enthusiastic crowd of tourists.