Lake Tonsee lies in the Teupitz lake district and is part of the Dahme-Heideseen Nature Park. Clay was mined here until the end of the 19th century. The mine was closed in 1900 and gradually filled with groundwater. The clear, clean water makes the lake a population destination for day visitors and holiday guests. There are two campsites by the lake. The lake is also particularly attractive for divers who value not only the excellent visibility but also the items that they find from the former clay mining activities there: Parts of trucks, rails and other things. Some of the relics are displayed alongside a display panel in the parking area above the bathing area.
The bathing area is immediately below the campsite on the eastern shore of the lake. The projecting sandy bathing area and the surrounding infrastructure of bistro, toilets and playground give a real holiday atmosphere. Parking is available for a fee above the bathing area. The water quality is regularly monitored by the district health authority in accordance with the Brandenburg Bathing Water Ordinance and is of excellent quality.