Lake Sääksi

Lake Sääksi (Sääksjärvi, or just simply Sääksi) is a 260-hectare large lake in Uusimaa, Finland. It is located on the border between the municipalities of Nurmijärvi and Hyvinkää, on the ridge formation called Salpausselkä. The villages of Röykkä and Kiljava is located near Lake Sääksi.

Lake Sääksi is a groundwater lake without a drainage ditch, and its water changes through the soil. The lake is very even in depth and the deepest part of the lake is about eight meters deep. The water in the lake is very clean, and the lake has a good oxygen situation. Alkalinity, which indicates the buffering capacity of lake water, is very low. Lake Sääksi is one of Finland's largest spring-based lakes.

The approximately 800-meter-long Sääksi Beach is popular especially among the residents of Nurmijärvi and Hyvinkää, but it also attracts visitors from other parts of Uusimaa.

The lake has been said to have served as a model for fictional Lake Ilvesjärvi in the 1870 novel The Seven Brothers by Aleksis Kivi.