Kleifarvatn, nearly 10 km2 and up to 97 m deep, the third largest lake in southern Iceland. The water level rises and falls at intervals according to precipitation. Formerly a dead lake, but some trout have been imported and are prospering.

At the crag Innri–Stapi on the shore there is a bronze plaque commemorating the guide Stefán Stefánsson, whose ashes were scattered in the lake, as he requested.