Røssvatnet

or is a lake and reservoir in the municipalities of Hattfjelldal and Hemnes in Nordland county, Norway. It has been the site of human occupation since the Stone Age. Its area of 219 km2 makes it the second largest lake in Norway by surface area. Without the dam which has regulated the lake since 1957, it would be 190 km2 and the third largest lake in Norway. Its depth is 240 m, its volume is estimated at 15 km3, and its surface elevation is 374 m above sea level. In the southern part, its largest island is situated. Røssvassholmen, with an area of 17.39 km2. The highest point of it, towering 206 metres above the lake's surface (at top regulation height). Røssvassholmen are Norway's second largest lake-island. The largest being; Helgøya within Mjøsa.