The Long Glacier (1355m) is the second largest in Iceland. It has an area of about 950 km² and most of it rises between 1200 and 1300 m above sea level. It rests on a massif of hyaloclastite mountains. They rise highest under its southern and northern parts, but have not yet been researched thoroughly. The Glaciological Society owns a hut at the foot of the nunatak Fjallkirkjan (1228m).

The southwestern part of the icecap is called Geitlandsjokull. It rises to the elevation of 1400 metres. On a fine day the view from up there is excellent. To the south of Geitlandjokull and separated from the main iceap, is the smaller, 1350 metres high Thorisjokull on top of an irregular table mountain. According to the legend, it was named after the ogre Thorir, who lived in a green valley in the pass between the glaciers.