Langisjór is a large lake southwest of Vatnajökull. It is 27 square kilometers, 20 km long and 2 km wide where it is widest. Altitude is 662 m. and it stretches southwest from the glacier. East of Langisjór is the mountain range Fögrufjöll, there are many rock formations that lead into the water and cross into the fjords and bays. On the southern end is Sveinstindur which is named after Sveinn Pálsson, a physician and naturalist from Vík. Sveinstindur is 1092 m above sea level.
It is relatively easy to walk up, so most people are able to get to the top with an increase of 400m. The view from the top is unique, it is said that if the weather is good you can see over á quarter of Iceland, from Öræfajökull in the east to Hellisheiði, Langjökull and Hofsjökull in the west. When looking over all of Langisjór the view is incomparable.
To the right is Fögrufjöll with numerous lagoons between high and peaks. East of Fögrufjöll runs the glacier river Skaftá, which often crashes with catastrophic floods, which originate in Skaftárkötlum, which are close to Vatnajökull. East of Skaftá you can see Lakagígar, where the lava from Skaftáreldar flooded the lowlands in 1783, that is the third largest lava flow on earth since the last ice age.
It is popular to go on kayaking trips in Langisjór.