Møsvatn (or Møsvann) is twelfth largest lake in Norway with a surface area of 78.31 km². It lies primarily in Vinje municipality in Telemark county. The lake lies in the watershed of the Skien river (Skiensvassdrag) and discharges into the Måna river. Along the shores of the lake, many traces of stone age settlers can be found. It is 919 meters above sea level and regulated to use for hydroelectric production.