Ventotene, in Roman times known as Pandateria, is one of the Pontine Islands in the Tyrrhenian Sea, 46 km off the coast of Gaeta right at the border between Lazio and Campania.
The island, the remains of an ancient volcano, is elongated, with a length of 3 km and a maximum width of about 800 m. The municipality includes the small ancillary island of Santo Stefano, located 2 km to the east, which is the site of a massive prison, now closed.
A further island, Ponza, is 40 km to the west.