Kallada River flows through Kollam district. This river originates from the Kulathupuzha hills near Ponmudi. This river which has a length of 121 kms flows through the places Pathanapuram, Kunnathur, Kottarakkara and Kollam. The end point of this river is the Ashtamudi Kayal. The river bed is usually rocky and it is difficult to swim and play in such as river. There are huge rocks, deep pits and other obstructions in the river.
The main tributaries of Kallada River are Kulathupuzha, Chenthurnipuzha and Kalthuruthipuzha. There is a famous Hanging Bridge built across the river and the famous tourist destination Palaruvi waterfall is also in this river.