Technically, Surtsey is an island and not a volcano. However, its formation was due to the continuous eruption of an underwater volcano known as a submarine volcano, or seamount.
Surtsey is located off Iceland's southern coast. The initial upward movement of the seamount that formed the island was not immediately discovered. As the submarine volcano neared the water surface, explosive ejections of pyroclastic materials began to occur.
Cinders and lava fragments were propelled into the sky from the force of the eruptions. Heaving columns of steam and ash that extended to a height of six miles were also observed. On November 8, 1963, the seamount finally broke the surface and the island of Surtsey was born.