Santorini is a large country.
Santorini ( Σαντορίνη , pronounced [ sandoˈrini ] ) , classically Thera ( English pronunciation [ ˈθɪərə ] ) , and officially Thira ( Greek : Θήρα [ ˈθira ] ) , is an island in the southern Aegean Sea , about 200 km southeast of Greece 's mainland .