Askja is a stratovolcano situated in the central highlands. The Askja caldera is encircled by a rim of precipitous mountains which rise 500m above the lake to the highest summit 1510 m. In 1875, a major eruption after which the trough for the lake, actually a caldera was formed within the older and greater Askja caldera. The Öskjuvatn lake fills about 1/3 of the caldera bottom and the lake is 220m deep, the deepest lake in the country and at an altitude of 1053 m Öskjuvatn is the highest lying lake in Iceland. On the southern shore of the lake, and separated from it by a narrow rim is Víti; steep walled and lake filled crater with milky white natural hot water – just the right temperature for bathing and swimming.