Located on the border between the 2 Italian Regions of Lazio and Campania, it measures 3 square km. Has been inhabited by ancient Greeks and Romans. Still visible are several ruins of Roman villas, aqueducts, the ancient port and fish ponds molded from the volcanic tuff rock tuff.  It is a marine park, perfect for lovers of snorkeling and diving. The Patron's celebration is on September 20, Festa di S. Candida .