Santorini caldera
Santorini caldera is a large, mostly submerged caldera, located in the southern Aegean Sea, 120 kilometers north of Crete in Greece. Visible above water is the circular Santorini island group, consisting of Santorini (classic Greek Thera), the main island, Therasia and Aspronisi at the periphery, and the Kameni islands at the center. It has been designated a Decade Volcano.