Sicily is directly adjacent to the Italian region of Calabria, via the Strait of Messina to the east. Lemons, oranges, lemons, olives, olive oil, almonds, and wine are among its other agricultural products. Most important provinces are Agrigento, Catania, Palermo, Syracuse and Trapani. Also part of various Sicilian provinces are small surrounding islands: Aeolian Islands. The island of Sicily is drained by several rivers, most of which flow through the central area and enter the sea at the south of the island. Sicily and its small surrounding islands are highly significant in the area of volcanology. Mount Etna is the only volcano on mainland Sicily located in the east; with a height of 3,320 m (10,900 ft) it is the tallest active volcano in Europe and one of the most active in the world. The Aeolian Islands to the north-east are volcanically significant with Stromboli currently active.