Flaajokull glacier (Fláajökull) is a small, slow flowing glacier of Iceland. It is located on the east side of volcano Breiðabunga in the east of Iceland, in Vatnajökull National Park northwest of the town Höfn í Hornafirði.
Fláajökull is a drain glacier of the large glacier Vatnajökull. The name derives from flár, the Icelandic word for “slope”. Historical names of the glacier are Mýrajökull, Hólmsárjökull and Hólsárjökull. The glacier–tongues Fláajökull and Heinabergsjökull stretch far down into the district. It is possible to drive to Fláajökull along Hólmsá.
Heinabergsjökull divides into two arms around the mountain Hafrafell, north of which there is another mountain, Snjófjall, with a peculiar glacier hollow on the south side. The valley Vatnsdalur (“Water (or lake) valley”) on the western side of Heinabergsjökull often collects large quantities of water dammed up by the glacier, Heinabergsvötn.
Once in a while this water forces its way out under the glacier, causing big floods in the rivers. The low mountain Jökulfell (150m) in front of Fláajökull was hidden by ice at the beginning of the century, but began to come into view around 1920.