Vamanapuram River is an 88-km long river in southern Kerala. The river originates in the Chemunjimotta hills (alt. 1860m) hills on the southern side of the Western Ghats, and flows through Thiruvananthapuram and Kollam districts of Kerala.It ends in AnjengoLake(Anchuthengu Lake) near kadkkavoor.other known as "kollampuzhayaru" The two tributaries of this river are the Upper Chittar & Manjaprayar streams.
Trivandrum longest river is vamanapuram river,famous antique temple keezhattingal subrahmanyan temple,kollampuzha thiruvarattu kavu devi temple is situated in this river bank. keralas famous boat race chirainkil boat race hoisting in this river. vamanapuram river side located most important town is attingal,so this river called "attingalaru"