Mannarasala Temple or the Nagaraja Temple is a popular center of pilgrimage for the devotees of serpent gods and also one of the best places to visit in Alappuzha. Of all the places of Serpent worship in the world, there is none that is more benign, oweinspiring and legendary than Mannarasala, as blessed and envisaged by Lord Parasurama, the creator of Kerala. In the light of experience, many devotees who have experienced and heard about the miraculous powers of the serpents and the presiding deities here, tell many stories about Mannarasala temple. It is not a rare thing to see the same serpent appear in the same location for a number of days in the temple premises. On the steps of the gatehouse, on the hedgerows, among the creepers; those who perform bhajanam in the temple can stand very close at any time and pray.
The most celebrated festival at Mannarassala is the Ayilyam of Thulam. The Ayilyam day in Tulam, Kanni and Kumbham months in the Malayalam calendar and the Mahasivarathri are celebrated here with great pomp. The Ayilyam in Kanni is the birthday of Nagaraja and that in Kumbham is the birthday of Anantha, the Muthassan of Nilavara (cellar). Parasurama, who installed the deities at the Mannarasala temple, also had given inviolable instructions to be followed to preserve the sanctity of the place, as well as to take care of the Naga deities in the blessed land made by him.