This is the only lake sanctuary in Kerala and is accepted to be the first seat of Ananthapadmanabha Swami. Legend has it this is the first site where Ananthapadmanabha settled down.

It is said that one day Lord Narayana showed up before him as a child. The kid's face was gleaming with brilliance and this overpowered the sage. He got restless and asked what his identity was. The kid answered that he had no dad no mother and none at home. Vilwamangalam had sympathy for the kid and permitted him to remain there. The kid proposed a condition that at whatever point he feels mortified he will leave the spot immediately. He served the sage for at some point. In any case, soon his adolescent tricks got unbearable for the sage and he responded brutally. Mortified the kid vanished from that point subsequent to announcing that if Vilwamangalam needs to see him he would need to go to Ananthankat, the timberland of snake god Anantha. 

Vilwamangalam before long understood that the kid was none however the lord himself and he had extraordinary contrition. He found a cavern at where the kid vanished and he continued further into the collapse search of the kid. He arrived at the ocean and continued further southward and finally, he arrived at a woody territory close to the ocean. Vilwamangalam saw the youngster who before long vanished into an immense illippa tree (Indian margarine tree or Mahua tree). Promptly the tree tumbled down and accepted the state of Lord Vishnu lying on a thousand hooded snake.