Karamana River, an important tributary of the Neyyar
, rises on the ridge to the north of Agasthiar Peak
and an outlying spur terminating in the Sasthamkotta Rock.
Initially, the river meanders towards west, and then towards south and south west. After a course of 66 km, this river system discharges into the Arabian Sea near Poonthura at the foot of the headland Kovalam. During it track, the river passes partially over the narrow rocky bed by high banks, through a comparatively wild woody and uneven country.
Aruvikkara, a famous tourist spot, is on the banks of the Karamana, 16 km from Thiruvananthapuram. Karamana, Aruvikkara Dam, Peppara Dam and Karamana Mandapam are some other places of tourist interest on this river.