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 and a 2011 census population of 15,550. The viticultural pride of the island is the sweet and strong Vinsanto (Italian: "holy wine"), a dessert wine made from the best sun-dried Assyrtiko, Athiri, and Aidani grapes and undergoing long barrel aging (up to twenty or twenty-five years for the top cuvées). It matures to a sweet, dark amber-orange, unctuous dessert wine that has achieved worldwide fame, possessing the standard Assyrtiko aromas of citrus and minerals, layered with overtones of nuts, raisins, figs, honey and tea. White wines from the island are extremely dry with a strong, citrus scent and mineral and iodide salt aromas contributed by the ashy volcanic soil, whereas barrel aging gives to some of the white wines a slight frankincense aroma, much like Vinsanto. It is not easy to be a winegrower in Santorini; the hot and dry conditions give the soil a very low productivity. The yield per acre is only 10 to 20% of the yields that are common in France or California. The island's wines are standardised and protected by the "Vinsanto" and "Santorini" OPAP designations of origin.