Surtsey

Volcanic island 20 km/12 mi southwest of Heimaey in the Westman Islands (Vestmannaeyjar) of Iceland. The island was created by an underwater volcanic eruption in November 1963, and is formed largely of ash with some lava flows. The island is the subject of intense scientific study, especially of its colonization by flora and fauna. Landing is strictly controlled.

The eruption that formed the island is what is termed phreatomagmatic, where sea water causes a rapid cooling of magma, enhancing its explosiveness. A smaller island was formed at the same time but was soon eroded by the sea and no longer exists. Descriptions of an island similar to Surtsey appear in accounts of St Brendan's voyages in the north Atlantic, adding credance to the theory of the discovery of Iceland by the Celts.