Þingvallavatn Lake
Lake Þingvallavatn lies in a rift valley that extends south from the Langjokull glacier to mount Hengill and from Botnssulur mountains in the west to Lyngdalsheidi heath in the east. The lake is the largest natural lake in Iceland, about 84 square kilometers, at an altitude of approximately 100 meters above sea level. The deepest part of the lake measures 114 meters, which means it reaches below sea level. The catchment area of Lake Thingvallavatn, about 1300 square kilometers, lies in the same direction as the fissure in the area, and its existence is closely connected with its geological history. The water in the lake is very cold and therefore very pure, so snorkeling and diving are popular. Silfra, one of the fissures in the northern part of the lake, is one of the most popular diving spots in Iceland.