Vellayani Lake which is locally called as Vellayani Kayal is in Thiruvananthapuram district. It is the largest fresh water lake in Thiruvananthapuram. A unique feature found here is a road that passes through the lake for which a bund has been built. The area around this lake is left unspoiled as the modern day construction works has not been done in this area. The water from this lake is being used for drinking and irrigational purposes. Now the water is getting polluted. Long ago, the area of this lake was around 750 hectares which then reduced to almost half the area in the recent years.
As it is at a distance of 7 kms from Kovalam, one who visits Kovalam should not miss this lake. The locals here call a portion of the lake as Kochu Kovalam. It is an important tourist destination. But there are no tourist facilities and shops here, so it advised to spend not more than an hour or two. Boat races are also conducted here during the festival Onam. There are two pilgrim centers near the bank of the lake namely the Vellayani Vishnu temple and Vellayani Devi temple.