Bergsee, Lake in Uslar, Germany.

Bergsee is a flooded former open-cast pit about 2 hectares in size, roughly 300 metres long and 50 metres deep, west of Delliehausen in the Solling, in the Solling-Vogler Nature Park. The pit filled with water from the Mühlenrodbach. An 800-metre circular path runs around the lake, a private campsite lies on the east bank and an artificial bathing beach on the north-west side.

The water body formed after mining operations extracted lignite and quartz sand from 1888 to 1911 and again briefly from 1945 to 1948. Once mining ended, a lake developed naturally in the former pit and became a protected natural monument in 1985.

The lake lies by the Haje settlement, and its name simply refers to the former open-cast pit, which filled with water from the Mühlenrodbach stream. An 800-metre circular path runs around the water, and a privately run campsite occupies the eastern shore. Since 1985 the lake has been protected as a natural monument, so boating is not permitted.

An 800 m circular path runs around the lake, and a privately run campsite sits on the eastern shore. The artificial bathing beach on the northwest side is no longer for swimming: the Dassel forestry office, as owner, banned bathing from 2021 because safety works and water-quality checks are not carried out. Boats are not permitted on the water.

What makes this place special is that it emerged from an industrial past, showing how nature itself can transform an exhausted mining site into a living space. This shift from former quarry to protected natural area makes it a story of natural recovery.