Lake Breidavatn actually consists of two lakes connected by a short stream on the outwash plain Breidaver. They are situated 564 m above sea level with an area of 0,36 kmē.  The greatest depth is 15 m and they contain about 1 Gl of water.

The average depth is 2,8 m, average length 1,3 km and average width 0,7 km. According to fishing reports they are not among the prolific lakes in the area.  Litla-Breidavatn is more prolific, but unstable. The best fishing spots are: Osinn, Tain, Fjara, Kverkin, The Outlet, Giggrunn and Gigbotn.  In addition there is one unnamed spot.