Kolumbo
Kolumbo (Greek: Κολούμπο) is an active submarine volcano in the Aegean Sea in Greece, about 8 km (5.0 mi) northeast of Cape Kolumbo, Santorini (Thira) island. The largest of a line of about twenty submarine volcanic cones extending to the northeast from Santorini, it is about 3 km (1.9 mi) in diameter with a crater 1.5 km (0.93 mi) across.