This lake is about 20 km long and up to 2 km wide and it extends almost up to the south-western edge of the largest icecap of Europe, Vatnajokull. Its greatest depth is 75 m, its area 27 kmē and it lies 670 m above sea level.

Almost all of its surroundings are barren mountain deserts and no documentation is found about its existence until in the latter part of the 19th century. The lake is dotted with many islands and the landscape is uniquely magnificent. Its discharge, Utfall, cascades into the glacial river Skafta. Only 4wd vehicles are recommended for a tour to the lake.
The Langisjor area is expected to become a part of the National Park Vatnajokull