Papanashini meaning "Washing of sins" is a river in Kerala. Papanashini has a story of its origin. Lord Brahma was making Vishnu’s idol and at the same time Garuda with a pot of nectar called Amrit Kumbha reached the installation place. When Garuda was completing his circling, one drop of Amrita fell into the stream, and hence the stream obtained the power of purification. After this incident, the stream was referred as Papanashini.

The Papansahini water is very useful to the Thirunelly temple. Pilgrims do not miss an opportunity to visit Papanasini River as they believe that this river washes their sins from them making them pure.