Femunden is Norway's third largest lake and the second largest natural lake in Norway. It is located in Innlandet and Trøndelag counties in Norway, just west of the border with Sweden. The lake lies primarily in the municipality of Engerdal (in Innlandet) and also smaller parts are located in the municipalities of Os (Innlandet) and Røros (Trøndelag). Femundsmarka National Park borders the northeastern part of the lake. The lake holds about of water and reaches a maximum depth of . The surface of the lake sits about above sea level. Name The first element (Fe- or Fem-) has no known meaning, and the last element is the suffix -mund or -und (both are common in Norwegian place names). History After Sweden had conquered the parishes of Idre and Särna in 1644 lake Femunden was considered to be part of the border between Norway and Sweden. But this was never officially recognised by Norway (or in reality by the Danish government, since Norway was ruled from Copenhagen in the early modern age), and during border adjustments in 1751 the Femundsmarka area east of the lake was granted to Norway from Sweden. The new (and current) border from 1751 is quite special: For a length of , it makes a completely straight line between the summits of the tall mountain Våndsjögusten and the tall mountain Østerhogna. Straight-line national borders are very unusual in Scandinavia, except in the very northernmost parts. See also List of lakes in Norway MS Fæmund II References External links National Park Brochure from 2011 (English) Map of Femund and the adjacent Femundsmarka National Park Stereoscopic 3Dpicture and field recording of the Femundsmarka National Park Engerdal Os, Innlandet Røros Lakes of Innlandet Lakes of Trøndelag Bifurcation lakes