Ponza is one of the Pontine Islands, or Ponza Islands, a volcanic island group in the Tyrrhenian Sea off the west coast Italy just to the north of Naples. The island is a popular summer resort and is good for its beaches, bays and snorkeling. The water is remarkably clear, and in the treacherous shallows of the Secca dei Mattom, between the islands of Ponza and Palmarola, archaeologists have uncovered a number of wrecks of Roman galleys dating from the Republican Period. Other sites of interest include the San Silverio church, Governor's Palace and a Fortress.