Klick here for a large view!

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, Greek Θήρα, IPA: ˈθira). It is the southernmost member of the Cyclades group of islands, with an area of approximately 73 km² (28 mi²), and in 2001 had an estimated population of 13,600. Santorini is essentially what has been left from an enormous volcanic explosion which destroyed the earliest settlements thereon and led to the creation of the current geological caldera. Its spectacular natural beauty along with its eminent nightlife make the island one of Europe's top tourist hotspots.

A giant central lagoon, more or less rectangular and measuring about 12 km by 7 km (8 mi by 4 mi), is surrounded by 300 m (984 ft) high, steep cliffs on three sides. The island slopes downward from the cliffs to the surrounding Aegean Sea. On the fourth side, the lagoon is separated from the sea by another much smaller island called Therasia. The lagoon merges with the sea in two places, in the northwest and southwest. The water in the centre of the lagoon is nearly 400 m (1,300 ft) deep, thus being a safe harbour for all kinds of ships. The island's harbors are all in the lagoon and there are no ports on the outer perimeter of the island. The island's capital, Fira, clings to the top of the cliff looking down on the lagoon.

It is the most active volcanic centre in the South Aegean Volcanic Arc, though what remains today is largely a water-filled caldera. The name of Santorini was given to it by the Latin empire in the thirteenth century and is a reference to Saint Irene. Before then it was called Kallistē ("the most beautiful one"), Strongylē ("the circular one"), or Thera.

The island is the site of one of the largest volcanic eruptions in recent prehistory: the Minoan eruption, which occurred some 3,500 years ago at the height of the Minoan civilization. The eruption left a large caldera surrounded by volcanic ash deposits hundreds of feet deep and, according to a theory, may have indirectly led to the collapse of the Minoan civilization on the island of Crete, 110 km (70 mi) to the south, through the creation of a gigantic tsunami. Another popular theory holds that the Thera eruption is the source of the legend of Atlantis (see below for detail).