An aperture on the Ionian coast below Castro leads into the magnificent stalactite-festooned Cave of Zinzulusa, one of the most significant coastal limestone karst formations in Italy. The portion accessible to the public stretches hundreds of metres back from the cliff face, terminating in a chamber grand enough to justify the sobriquet 'Il Duomo'. Divided into three distinct geomorphological sections, Zinzulusa is home to endemic crustacea and other 'living fossils' known nowhere else on the planet.