Ringsjön is a lake situated in the middle of Skåne County, Sweden. At 41 square kilometres (10,100 acres), it is the second largest lake in the county. The western and eastern parts of the lake, called Västra Ringsjön and Östra Ringsjön respectively, are separated by a headland. Västra Ringsjön has a depth of 6 metres (20 ft) at its deepest known point, while Östra Ringsjön has a depth of 17 metres (56 ft). Ringsjön provides drinking water for the inhabitants of Skåne if the water tunnel connected to the lake Bolmen would cease to work.
https://en.wikipedia.org/wiki/Ringsj%C3%B6n