Santorini classically Thera and officially Thira, is an island in the southern Aegean Sea, about 200 km (120 mi) 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.Santorini's primary industry is tourism. The two main sources of wealth in Santorini are agriculture and tourism. In recent years, Santorini has been voted one of the world's most beautiful islands