Grímsvötn is a subglacial volcano located in Iceland, beneath the Vatnajökull glacier. It is one of the most active volcanoes in the country, with its last significant eruption occurring in 2011. The volcano is known for its explosive eruptions, which can produce large ash clouds and melt significant amounts of ice. The geothermal heat from Grímsvötn causes the glacier above to melt, creating a large lake. When pressure builds up from the melting water, it can lead to sudden jökulhlaups, or glacial floods, which can impact nearby areas. Monitoring this volcano is crucial for understanding its behavior and potential hazards.