Sasthamcotta Lake is the largest freshwater lake in Kerala, India. It is located at Sasthamcotta, in Kollam district.  It is a Ramsar site and a wetland of international importance, under the Ramsar Convention. It is spread over an area of 375 hectares.

Sasthamcotta Lake is named after the Sastha temple,  located on the banks of the lake. Cavaborus Larva consumes the bacteria found in the lake waters and thus purifies the water. The lake waters are the main source of drinking water in Kollam City.

Except for an earthen dam on the southern side of the lake, which has a length of 1.5 kilometers, all other sides are surrounded by hills. Varkala formations are observed along the coastal beds in the state of Kerala. Varkala Geological formations are believed to be formed 66 million to 2.6 million years ago.

Fishing in the lake is allowed and is a significant source of income for the local people. Neendakara fishing harbor, a major fishing harbor in the state, is around 20 kilometers from this lake.

This lake is the habitat of 27 species of freshwater fishes and two species of prawns. 21 species of herrings and sardines are also found in this lake waters.

There are no visible tributaries feeding Sasthamcotta Lake, though it is situated in very close proximity to the Kallada River. Sasthamcotta Lake is located in the northern side of Ashtamudi Lake, the gateway to the backwaters of Kerala. Ashtamudi Lake is another Ramsar site and the second-largest backwater in Kerala.

How Do I Go to Sasthamcotta Lake?

Sasthamcotta Lake is around 27 kilometers from Kollam city. This town and lake are also known as Sasthamkotta Lake or Sasthankotta Lake.

Sasthamcotta Lake is easily accessible by road. It is situated on the side of National Highway 183A, which connects the Titanium Dioxide Factory Junction at Chavera to Vandiperiyar via Adoor, Pathanamthitta, Angamoozhy, Kakki, and Gavi. At Chavra,  NH 183A  joins with NH 66 (Panvel- Kanyakumari National Highway). At Vandiperiyar, NH 183A  merges with NH 183.

Karunagappally railway station is the nearest to the lake; very few trains stop here. Kollam Junction railway station is the closest major railway station to Sasthamcotta.