Lake Brunnavatn has an area of 0,6 km². It is rather shallow and is situated at 369 m above sea level east of the valley Bardardalur.
Its discharge tributes to the river Skjalfandafljot. It is accessible by 4wd vehicles. The catch is mainly small Lake Chars.
The distance from the capital is about 472 km by the Whale Bay tunnel and 83 km from Akureyri.