The glaciers of Iceland cover 11.1% of the land area of the country (about 11.400 km² out of the total area of 103.125 km²) and have a considerable impact on its landscape.
Many Icelandic glaciers lie above volcanos, such as Grímsvötn and Bárðarbunga, which lie under the largest glacier, Vatnajökull. The caldera of Grímsvötn is 100 km², and Bárðarbungu is 60 km². When volcanic activity occurs under the glacier, the resulting melt water can lead to a sudden glacial lake outburst flood known in Icelandic as jökulhlaup but jökulhlaup are most often caused by accumulation of meltwater due to geothermal activity underneath the glacier. Such Jökulhlaup have occasionally triggered volcanic eruptions because of the sudden release of pressure. The Icelandic word for glacier is jökull.
These 13 largest glaciers have an aggregate area of 11.181 km² (compare to about 11.400 km² for all glaciers of Iceland).