Lake Hagavatn has an area of about 1,3 km², its greatest depth is 8 m and it lies 19 m above sea level. Its discharge is River Stadara.

The catch consists of sea trout, sea char and salmon. Two rods are permitted for the river per day and more for the lake. A legendary creature, a reverse hoofed horse, is said to live in a small pond near the lake.

The distance from the capital is 159 km by the Whale Bay tunnel and 91 km from Borgarnes.