Iceland 21.May 2011: Volcanic eruption in Grimsvotn, Vatnajokull glacier, Iceland. They lie in the highlands of Iceland at the northwestern side of the Vatnajokull glacier and are covered by its ice cap. The eruption plume had risen to an altitude of over 65,000 ft (~20 km). The last eruption in Grimsvotn occurred in November 2004. Grimsvotn is Iceland's most frequently erupting volcano.