Banasura Sagar dam across the Karamanathodu River, a tributary of River Kabini, near to Kalpetta, is considered to be the largest earth dam in India and the second largest in Asia. The dam is ideally placed in the foothills of Banasura hills, which got its name from 'Banasura', the son of King Mahabali, the famous ruler of Kerala. It is said that 'Banasura' undertook severe penance on the top of the hills. Banasura hill is the third largest peak in the Western Ghats.