This lake has an area of about 1,45 km². It is 47 m deep and is located 73 m above sea level. It is used as a reservoir, which causes fluctuations in its –level and the greatest difference reaches 6 m. To the west of the lake is the valley Thidreksvalladalur, green and inviting for farming. At the end of the lake in the valley are the ruins of the farms Thidreksvellir and Vatnshorn.
Its discharge is Thvera, which empties into the bay Steingrimsfiord. The catch consists of brown trout and lake char. There is no limit to the number of permits issued per day.
The distance from the capital is about 275 km and 5 km from Holmavik.
Thidreksvallarvatn in Icelandic