The Vamanapuram River originates from the Chemunjimotta hills of the Western Ghats
. It is also called Attingal River. Flowing westwards for about 80 km, the Vamanapuram is one of the major rivers in Thiruvananthapuram District
. The Upper Chittar and Manjaprayar are the tributaries of this river.
The Vamanapuram River supplies water to the community of Vamanapuram village. The river meanders its way to the Anchuthengu back waters through Attingal town. Koikkal Bhagavathi Temple in Attingal lies on the banks of this river.