Grímsvötn is an active volcano with a fissure system located in Vatnajökull National Park, Iceland. The central volcano is completely subglacial and located under the northwestern side of the Vatnajökull ice cap. The subglacial caldera is at 64°25′N 17°20′W / 64.417°N 17.333°W, at an elevation of 1,725 m. Beneath the caldera is the magma chamber of t…Grímsvötn is an active volcano with a fissure system located in Vatnajökull National Park, Iceland. The central volcano is completely subglacial and located under the northwestern side of the Vatnajökull ice cap. The subglacial caldera is at 64°25′N 17°20′W / 64.417°N 17.333°W, at an elevation of 1,725 m. Beneath the caldera is the magma chamber of the Grímsvötn volcano.