Vatnajökull (English: Glacier of lakes) is the largest glacier in Iceland. It is located in the south-east of the island, covering more than 8% of the country. With an area of 8,100 km², it is the largest glacier in Europe by volume (3,100 km³) and the second largest (after Austfonna on Nordaustlandet, Svalbard) in area (not counting the still larger ice cap of Severny Island of Novaya Zemlya, Russia, which may be regarded as located in the extreme northeast of Europe).

The average thickness of the ice is thus 400 m, with a maximum thickness of 1,000 m. Iceland's highest peak, Hvannadalshnúkur (2,110 m), is located in the southern periphery of Vatnajökull, near Skaftafell National Park. It is classified as an ice cap glacier.

Under the glacier, as under many of the glaciers of Iceland, there are several volcanoes. The volcanic lakes, Grímsvötn for example, were the sources of a large jökulhlaup (glacial lake outburst flood) in 1996. There was also a considerable but short-time eruption of the volcano under these lakes at the beginning of November 2004. During the last ice age, numerous volcanic eruptions occurred under Vatnajökull, creating many subglacial eruptions. These eruptions formed tuyas, such as Herðubreið which was beneath Vatnajökull during the last ice age.

According to Guinness World Records, Vatnajökull is the object of the world's longest sight line, 550 km from Slættaratindur, the highest mountain in the Faroe Islands. GWR state that "owing to the light bending effects of atmospheric refraction, Vatnajökull (2119m), Iceland, can sometimes be seen from the Faroe Islands, 340 miles (550km) away". This may be based on a claimed sighting by a British sailor in 1939. The validity of this record is analysed/undermined in mathematical and atmospheric detail by J.C. Ferranti.

credited to wikipedia