Capo Caccia · Porto Conte Park
Neptune's Caves
The karst palace beneath Capo Caccia, 14 km from Alghero
✽ 14 km — 25 min by car
Neptune's Caves are a karst cave complex extending for over four kilometres beneath the Capo Caccia promontory, of which 200 metres are visitable. Discovered in the 18th century by fishermen searching for coral, they owe their name to the spectacular Smith Hall where the vault rises twenty-five metres and stalactites, stalagmites and columns create a natural architecture reminiscent of an underground cathedral. Inside, Lake Lamarmora — one of Europe's largest underground salt lakes — completes the scene.
Geological history and discovery
The caves were formed over millions of years by karst erosion of the Capo Caccia limestone. The current entrance, at sea level, was once partly submerged. The first documented explorations date from the 18th century, when Alghero coral fishermen reported their existence. The first scientific survey was conducted in 1821 by the geologist Alberto Ferrero della Marmora — from whom the interior lake takes its name. They were opened to the public in 1955 with the construction of the Cabirol Staircase (Escala del Cabirol in Alguerese, "Stairway of the Roe Deer"), 656 steps cut into the cliff.
What you see inside
The 200-metre tour, about 45 minutes long, takes in all the most spectacular halls. After the entrance, you enter Lake Lamarmora (120 metres long, salt water like the sea), pass the "Holy-Water Font" column, reach the Royal Hall with its great column twenty-two metres tall, and finally the Smith Hall with the famous "stone organs" — slender stalactites that produce sound when touched by the wind. Light reflections on the lake's water create unique colour effects. Interior temperature: a steady 15–16°C all year round — bring a sweatshirt, even in summer.
How to get there: stairs or boat
Two ways to reach them. By boat: departure from Alghero harbour, 45-minute crossing along the western coast, with spectacular views of Capo Caccia. Linea Grotte and Navisarda companies, price €15–20 return + caves ticket €14. Ideal for those who don't want to face stairs and would like a mini-cruise. On foot: from the Capo Caccia road, you descend the 656 Cabirol Staircase steps — a scenic but demanding route, especially on the way up. Free parking at the top. Note: with rough seas, boat departures are suspended; in strong winds, the staircase also closes. Before setting off, check the site grottadinettuno.it. Booking recommended in high season.