Flensjøen is a lake on the border of Innlandet and Trøndelag counties in Norway. The lake lies in the municipalities of Røros (in Trøndelag county) and Os (in Innlandet county). The lake lies about southeast of the town of Røros, about half-way between the lakes Korssjøen and Femunden, and about south of Håsjøen. See also List of lakes in Norway References Røros Os, Innlandet Lakes of Innlandet Lakes of Trøndelag