Lake Langavatn has an area of about 0,8 km², its greatest depth 8 m and the it is located 12 m above sea level. Its discharge is Kraeknalaekur, which empties into the ocean, but no visible water enters it.
Road 54 runs just south of it on the low coastal gravel ridge Olduhryggur. The catch consists mainly of 2-3 pound brown trout.
The distance from the capital is 154 km by the Whale Bay tunnel and 85 km from Borgarnes.