With a catchment area of 1987.17 sq km, River Pampa or Pamba is the third largest river in Kerala. The well-known temple of Sabarimala, which is visited by millions every year, is sitiuated on its banks. Legend has it that it was on the banks of the river that Ayyappa, the lord of the temple, made his appearance as a new born child to be adopted by the Pandalam Raja. It is a holy river for the devotees who visit the temple.

The river originates from Peerumedu in Idukki and flows through different places like Ranni, Thiruvalla, Changanasserry and Ambalappuzha, before emptying itself into the Vembanad Lake, the largest lake in Kerala and one of the largest in India itself. The Poonthenaruvi waterfall is an added attraction to the area.