volcanic island group in the Tyrrhenian Sea off the west coast of south-central Italy. The islands include Ponza (the largest), Palmarola, and Zannone in a western cluster and Ventotene and Santo Stefano in an eastern group. The highest point of the island of Ponza is Monte Guardia (928 feet 【283 metres】).

Regular steamer services connect Ponza with Naples and, in the summer, with Anzio and Formia. Kaolin (china clay) and bentonite are mined on the islands, which have become popular as summer resorts. Used since ancient times as places of exile, Ventotene has a prison, and Ponza was a place of banishment for political prisoners under the fascist regime. Area 4.2 square miles (10.9 square km). Pop. (2006 est.) 3,214.