or is a lake in the municipalities of Røyrvik and Lierne in Trøndelag county, Norway. The lake lies just south of the large lake Limingen, and just west of the border with Sweden. It is above sea level and has a volume of . The deepest part of the lake is deep. It is the seventh largest lake in Norway. Gudfjelløya The island Gudfjelløya () lies in Tunnsjøen lake. It has a high point of above sea level, which is higher than the lake. This makes Gudfjelløya the highest island on a lake in Norway. References Lierne Røyrvik Lakes of Trøndelag