Lake Ulfsvatn has an area of 3,85 km². It is rather shallow and situated at 434 m above sea level. It is the second largest lake on the moor and is fed by the river Gilsbakkaa, which collects water from a few lakes to the north. Its discharge, Ulfsvatnsa, feeds the lakes Grunnuvotn.
It is a good lake char and brown trout fishing lake and the fish gets quite large in size (8 pd). During earlier times the lake was vigorously netted. A hut, where up to 20 people can be accommodated, stands on its northeast banks. A 4wd track leads to the lake and the hut from the south.