Sicily is directly adjacent to the Italian region of Calabria, via the Strait of Messina to the east. The early Roman name for Sicily was Trinacria, alluding to its triangular shape. Sicily has been noted for two millennia as a grain-producing territory. Citrons, oranges, lemons, olives, olive oil, almonds, and wine are among its other agricultural products. The mines of the Enna and Caltanissetta district became a leading sulfur-producing area in the 19th century but have declined since the 1950s.

Administratively Sicily is divided into nine provinces; Agrigento, Caltanissetta, Catania, Enna, Messina, Palermo, Ragusa, Syracuse and Trapani. Also part of various Sicilian provinces are small surrounding islands: Aeolian Islands of Messina, isle of Ustica (Palermo), Aegadian Islands (Trapani), isle of Pantelleria (Trapani) and Pelagian Islands (Agrigento).

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. The Salso River flows through parts of Enna and Caltanissetta before entering the Mediterranean Sea at the port of Licata. To the east the Alcantara in the province of Messina, it exits at Giardini-Naxos. The other two main rivers on the island are to the south-west with Belice and Platani.

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. As well as Etna, there are several non-volcanic mountain ranges in Sicily, Sicani to the west, Eeri in the central era and Iblei in the south-east. Across the north of Sicily there are three other mountains Madonie, Nebrodi and Peloritani.

The Aeolian Islands to the north-east are volcanically significant with Stromboli currently active, also in the Tyrrhenian Sea are the three dormant volcanos of Vulcano, Vulcanello and Lipari. Off the Southern coast of Sicily, the underwater water volcano of Ferdinandea, which is part of the larger Empedocles last erupted in 1831. It is located between the coast of Agrigento and the island of Pantelleria (which itself is a dormant volcano), on the Phlegraean Fields of the Strait of Sicily.