Austfonna is an ice cap located on Nordaustlandet in the Svalbard archipelago in Norway. Covering an area of 7,800 km, it is Europe's third-largest glacier by area and volume, after the Severny Island ice cap of Novaya Zemlya, Russia, and Vatnajökull in Iceland. The combined area of Austfonna and the Vegafonna ice cap is 8,492 km.

Austfonna has a thickness of up to 560 metres (235 meters average thickness), and is 200 km in circumference. The ice dome reaches an elevation of 783 meters above sea level.

The southern third of Austfonna is sometimes called Sørfonna, which is a separate ice cap, separated from the main part of Austfonna by a long, ice-filled depression, and forming a separate crestal dome.

Vegafonna ice cap in the southwest is also connected to Austfonna proper, specifically to Sørfonna, and is separated from it by Erica Valley. Vegafonna also forms a separate dome. Immediately west of Vegafonna is Glittne ice cap, which is considered part of the former.

Vestfonna in the northwest of the island is a totally separate ice cap (the third largest of Svalbard and Norway).

• List of glaciers in Svalbard
• List of glaciers in Norway

• Spatial and temporal variability in snow accumulation on Austfonna, Svalbard.
• http://www.cig.ensmp.fr/~iahs/sapporo/abs/jsh01/020760-1.html
• http://www.cpom.org/research/largeice.htm
• Map of Nordaustlandet
• Livescience page