Coordinates: ISN93 403479 E, 393933 N
Lat: 0°, Lon: 0°
Álftavatn, a shallow lake through which flows the river Sog. The Sog is so wide and slow–moving below the lake that a rise in the level of Ölfusá River, beyond Sog, can cause it to back up and raise the level of the lake. Extensive birchwoods near the lake make it a popular area for summer houses.