The Edersee is a large reservoir created by the construction, from 1908 to 1914, of a rock and concrete dam across the Eder river to generate hydropower and regulate water levels for shipping on the Weser river. It lies at the northern edge of the Kellerwald.
In World War II, the dam was as part of Operation Chastise, destroyed by special bouncing bombs. Because of the peculiar shape of the lake, several attempts had to be made to get to the dam to drop the bomb.
At low water, in late summers of dry years, the remnants of three villages (Asel, Bringhausen, and Berich), along with a bridge across the original river bed, that were submerged when the lake was filled in 1914, can be seen, and descendants of people buried in the now submerged cemeteries go to visit the graves of their ancestors.