Grotta di Nettuno (Neptune's Grotto)

Grotta di Nettuno, or Neptune's Grotto, is one of Italy's most spectacular sea caves, hollowed into the sheer limestone cliffs of Capo Caccia near Alghero in north-western Sardinia. Inside, a guided walkway threads past forests of stalactites and stalagmites, soaring rock columns, and delicate flowstone formations, all reflected in the still waters of Lake Lamarmora, one of the largest saltwater lakes in any European cave. The cave was discovered by local fishermen in the eighteenth century and has drawn visitors ever since for its cathedral-like chambers and theatrical lighting. There are two ways in. The more dramatic is the Escala del Cabirol, a staircase of 654 steps carved into the cliff face that zigzags down from the Capo Caccia headland with vertiginous views over the sea; the easier option is a tour boat from Alghero's port, a passage of around forty minutes along the coast that is itself part of the experience. Inside, visitors follow a guided route lasting roughly forty-five minutes to an hour over paved but often wet and uneven surfaces. Including the boat trip or staircase, a full visit takes about two hours. Tickets cost around thirteen euros, with the boat fare separate. The cave is open mainly from April to October, and rough seas can suspend the boats, leaving the steep staircase as the only access or closing the site altogether. Mornings on calm days are best, both for softer light on the cliffs and to arrive ahead of the larger tour groups. Photography is allowed along the lit walkway, though tripods are impractical in the narrow, crowded passages. Children generally enjoy the underground lake and dramatic chambers, but the long staircase and dark, damp footing call for care, making sensible shoes a must for everyone.