West of Ponza, at about 8 miles, Palmarola is the most interesting island from a geologic point of view. Even if it is barer and drier, it is characterised by multicolour volcanic rocks creating shelters and outcrops of obsidian, a precious black volcanic stone. Despite its little extent, it is a real earthly paradise thanks to its loneliness and silence, its clear and deep waters, its wonderful depth. During the centuries, Palmarola has been a monastic retreat and deportation island. Today the island, which is officially uninhabited and fills up with people only in summer, is a wildlife reserve.