Þingvallavatn

Þingvallavatn
Fissures at the lake
Location	Þingvellir National Park
Coordinates	64°11′N 21°09′W / 64.183°N 21.150°W / 64.183; -21.150Coordinates: 64°11′N 21°09′W / 64.183°N 21.150°W / 64.183; -21.150
Primary outflows	Sog
Basin countries	Iceland
Surface area	84 km2 (32 sq mi)
Average depth	34 m (112 ft)
Max. depth	114 m (374 ft)
Water volume	2.856 km3 (0.685 cu mi)
Residence time	11 months
Islands	Sandey

Þingvallavatn, anglicised as Thingvallavatn, is a rift valley lake in southwestern Iceland. With a surface of 84 km² it is the largest natural lake in Iceland. Its greatest depth is 114 m. At the northern shore of the lake, at Þingvellir (after which the lake is named), the Alþingi, the national parliament, was founded in the year 930, and held its sessions there until 1799 and still as of today the name Alþingi Íslendinga is carried by the parliament of Iceland.

The lake lies partially within Þingvellir National Park. The volcanic origin of the islands in the lake is clearly visible. The cracks and faults around it, of which the Almannagjá ravine is the largest, is where the Eurasian and North American tectonic plates meet. Silfra fissure is a popular scuba and snorkeling site. The only outflow from lake Þingvallavatn is the river Sog.

One of the noted features of the lake is the presence of four morphs of the Arctic charr.