Breimsvatn or Breimsvatnet is a lake in the municipalities of Gloppen and Sunnfjord in Vestland county, Norway. At 22.67 km2, it is the largest lake in Gloppen (followed by the lake Emhjellevatnet). The European route E39 highway runs along the north end of the lake, connecting the two nearby areas of Sandane and Byrkjelo. On the shores of the 17 km long lake lie several villages including Re and Kandal. The lake flows into the Gloppenelva river which flows into the Gloppefjorden, an arm of the Nordfjorden. Historically, the area surrounding the lake was part of the municipality of Breim, which existed from 1886 until 1964.