Santorini , is an island in the southern Aegean Sea, about 200 km southeast of Greece's mainland.
It is the largest island of a small, circular archipelago, which bears the same name and is the remnant of a volcanic caldera. It forms the southernmost member of the Cyclades group of islands, with an area of approximately 73 km2.
The municipality of Santorini includes the inhabited islands of Santorini and Therasia and the uninhabited islands of Nea Kameni, Palaia Kameni, Aspronisi, and Christiana.
The total land area is 90.623 km2. Santorini is part of the Thira regional unit.
Santorini is essentially what remains after an enormous volcanic eruption that destroyed the earliest settlements on a formerly single island, and created the current geological caldera.
The main island slopes downward to the Aegean Sea.