Surtsey (English Surts Island), small island, Iceland, off the southern coast. Surtsey was formed by volcanic action that began with an eruption in November 1963. Two years later, the lava flow ceased and the island, 2.6 sq km (1 sq mi) in area, was designated a nature reserve. Biological, geological, and meteorological research is conducted on the island, which is named for Surtur, the god of fire in Scandinavian mythology.