Jökulsárlón is the best known and the largest of a number of glacial lakes in Iceland. It is situated at the south end of the glacier Vatnajökull between Skaftafell National Park and Höfn. Appearing first only in 1934-1935, the lake grew from 7.9 km˛ in 1975 to at least 18 km˛ today because of heavy melting of the Icelandic glaciers. Approaching a depth of 200 m, Jökulsárlón is now probably the second deepest lake in Iceland. The lake is filled with icebergs, which are calving off the Breiđamerkurjökull glacier. Near Jökulsárlón, there are two other glacial lakes, Fjallsárlón and Breiđárlón.
Jökulsárlón is separated from the sea by only a short distance, and the combined action of the glacier, the river that empties from the lake, and the ocean may eventually transform it into an inlet of the sea. There are plans to prevent this from happening, since the only road in the area passes over the narrow isthmus.
At its shore, in the summertime, one has to watch out for the skúas, big seagulls which have their nests on the ground around the lake and which can occasionally become aggressive.