Der Lungerersee, auch Lungernsee, seltener Lungerensee geschrieben, ist ein Naturstausee im Kanton Obwalden. Der See kann vom Brünigpass oder von Luzern her durch das Sarneraatal erreicht werden. An dem See liegt der Ort Lungern sowie dessen Ortsteile Kaiserstuhl-Bürglen und Obsee.
Lake Lungern is a small natural lake in Obwalden, Switzerland which is named after the town Lungern on its shore. The lake is drained by the Sarner Aa river, which flows through the Sarnersee and into Lake Lucerne.
The lake was originally much larger, and covered a large part of the valley it is situated in. Starting in 1836, its level was lowered by 36 metres through an artificial drainage tunnel of 380 m length. It is used as reservoir.