Kåsjön, Lake and nature area in Västra Götaland, Sweden.

Kåsjön is a freshwater lake in Västra Götaland surrounded by woodlands and meadows. An interconnected trail network allows visitors to explore varied natural environments throughout the area.

Kåsjön is a fissure-valley lake formed after the last ice age, when the sea briefly reached its level of about 109 metres. In the early 1500s a man named Kåre settled with his family on the eastern shore, living by farming, fishing and hunting; the name is a shortening of Kåres sjö. In the 1980s liming was begun to counter acidification, and it continues periodically.

Local people use this lake for swimming during warmer months and enjoy walks through the connected trails. The pathways draw outdoor enthusiasts who experience the changing landscapes between surrounding areas.

The area is accessible by public transportation with bus stops nearby providing access to trail entrances. Visiting in drier weather makes walking the paths easier and more comfortable.

The lake is a source lake: groundwater seeps up into it rather than feeding it through surface inflows. Its position a few metres below the highest post-glacial coastline and the acidic, hard-weathering bedrock around it leave the water with little buffering capacity, so liming operations have been carried out since the 1980s and continue periodically.