Sasthamkotta Lake is a freshwater lake in Kollam district. It is a very large lake that is bordered by trees on three sides. The total area of the lake is around 375 hectares and the view of the lake is breathtaking. It is surprising to note that the water is available throughout the year and does not get frozen up during winter or dry up during summer. The freshwater is very clear and there are no plants or weeds growing in the lake. This is an important tourist destination. Pedal boating is allowed whereas motor boats are not allowed in this lake.
A larva called as Chaoborus is present in this lake which feeds on viruses and bacteria making the water free of impurities. This pure water is supplied for drinking purposes in almost the whole of Kollam. There is a Dharma Shasta temple nearby which is an important pilgrim center. The place got the name Sasthamkotta from this temple.