Is Sicily Really Only One Island? ...
Sicily is indeed formed by the main island surrounded by groups of minor islands, which cover 1.11% of the entire regional surface (about 285.4 km² of the total 25,711 km²). Sicily included, there are 19 inhabited islands (there are 33,172 people living in the minor islands).
The main groups of islands of Sicily are the Aeolian islands, the Egadi Islands and the Pelagie islands; the Stagnone and Cyclopes islands are two small small groups of Islands off the west and east coasts of Sicily respectively, in front of Marsala (in the Trapani province) and Aci Castello (in the Catania province).
Ustica and Pantelleria, in the Thyrrenean sea and the Sicilian Channel respectively, are two municipalities of Palermo and Trapani province. The historical centres of Siracusa and Augusta (Siracusa province) are located on two islands which are connected to the main land.
From a geographical point of view even the Calipsee Islands, which form the Republic of Malta, could be considered a part of Sicily.
On the other hand, the Pelagie islands (especially Lampedusa and Lampione), are a marginal territory of the Italian republic and from geographical point of view, they are part of the African continent. Going to the minor islands by boat or hydrofoil
If you want to reach the minor islands, you have several options
The main boat companies are Usticalines http://www.usticalines.it/
And Siremar http://www.siremar.it/.
You can find all the info about prices and timetables on the websites or in the ticket offices at the respective port
How to get there: you can reach Ustica from Palermo by hydrofoil with Usticalines in about an hour and a half, (a one-way ticket costs around €25), and by ferry with Siremar in about three hours.
Info and tips: Ustica has a protected marine area which was the first marine reserve, established in 1986. The reserve is rich in marine flora and fauna and has similar characteristics to a tropical environment, which makes Ustica a really popular destination among scuba divers. While you are diving within corals and sea anemones, it is not uncommon to meet parrotfish, lobsters and giant groupers.