Signposted off the main coastal road some 10km south of the port, this huge and atmospheric cave remains impressive despite much looting of stalactites and stalagmites in the past. In December 1673, Marquis de Nointel held Christmas Mass here. He and other luminaries (including King Otto and Queen Amalia of Greece) have left their graffiti on the rock formations over the centuries. Descending the 400-plus steps will give you thighs of steel. A bus runs here from the port (€1.80).