Lake Kalfaborgararvatn has an area of 3,5 km². It is quite deep and is situated at 359 m above sea level east of the valley Bardardalur.  Its discharge is Kalfaborgara, which tributes to river Skjalfandafljot. The lake is accessible by 4wd vehicles from the west and east. The catch consists mainly of brown trout (½-3 pounders).

The distance from the capital is about 458 km via Akureyri by the Whale Bay tunnel.