Austfonna,
with a glacier front of 200 km long, is the world's third-largest
icecap after Antarctic and Greenland. This
is the largest glacier of Europe. The thickness of ice of Austfonna
is of more than 560 m. A great part of the base is under the sea level,
just like in Greenland and in Antarctica.
A significant number of glaciers in Svalbard from time to time advance
with extraordinary high velocity, up to several kilometers during
3-6 years (surge).
Between 1936 and 1938 a 30 km wide sector of the large ice cap on
Nordaustlandet, Austfonna, experienced a surge advance of more than
20 km into the ocean. This is presumably the longest surge advance
ever recorded at any glacier.