Santorini is a small circular archipelago of volcanic islands located in the southern Aegean Sea about 200 km south-east from Greece's mainland. It is also known as Thera (or Thira), forming the southernmost member of the Cyclades group of islands, with an area of approximately 73 Km2 ( 28 mi2 and a 2001 census population of 13,670. It is comprised of the Municipality of Thira (pop. 12,440) and the Community of Oia ( pop. 1,230, which includes 268 inhabitants resident on the offshore island of Thirasia, lying to the west). They have a total land area of 90.623 km², which also includes the uninhabited islands of Nea Kameni, Palaia Kameni, Aspronisi, and Christiani (all part of the Municipality of Thira).

Santorini is essentially what remains of an enormous volcanic explosion, destroying the earliest settlements on what was formerly a single island, and leading to the creation of the current geological caldera. Its spectacular physical beauty, along with a dynamic nightlife, have made Santorini one of Europe's tourist hot spots.