Lungerersee, Lake and reservoir in Obwalden, Switzerland.

Lungerersee is a natural lake located in a narrow alpine valley, shaped by surrounding mountain slopes. The water body is fed by small mountain streams and bordered by forests and meadows that descend toward the shore.

Around 1700 the idea of lowering the lake was first discussed to gain farmland for Lungern. Work began in the 18th century, splitting the village into "Nassen" (opponents) and "Trockenen" (supporters). A 420-metre drainage tunnel was completed in 1836, lowering the water from 675 to 657 m above sea level and creating 170 hectares of land. In 1921 the lake was dammed for hydropower, and the gained land was lost again.

The lake is marketed as a "fishing paradise", and Lungern has a lakeside bathing area and a sailing school. At the southern end a campsite sits directly on the shore. The 175th anniversary of the lake's lowering was marked by the documentary film "Härdepfel im See" by Luke Gasser and Riodi Gasser.

The lake level drops by up to 40 metres in winter because of power generation, exposing a wide strip of shore; the water returns with the spring snowmelt. A viewpoint on the cantonal road toward the Brünig Pass at Chälrütirank looks over the lake and much of the Sarneraatal. A campsite sits directly on the lake at the southern end, and Lungern has a lakeside bathing area and a sailing school.

In March 1999, two bodies cemented into oil drums were found on the shore at low water. The murderer, from western Switzerland, did not know that the lake level drops in winter and exposes a wide strip of shore.