Neptune's Grotto

Photograph by Anas Morsali, taken during his own trip

Grotta di Nettuno (Neptune's Grotto) is one of the most spectacular marine caves in the Mediterranean, located at the base of the towering Capo Caccia promontory near Alghero in northwestern Sardinia. Discovered by local fishermen in the 18th century, the cave extends approximately 4 km into the limestone cliff, though only a portion is open to visitors. Inside, visitors are greeted by a breathtaking underground world of stalactites and stalagmites that have formed over millions of years, reflected in the still waters of Lago Lamarmora — one of the largest saltwater lakes found inside a cave in Europe. The formations bear evocative names like the Grand Organ, the Royal Tribune, and the Christmas Tree, each illuminated to highlight their extraordinary shapes. Access is possible by boat from Alghero's port (a scenic 25-minute journey along the dramatic coastline) or by descending the Escala del Cabirol — a dramatic stairway of 656 steps carved into the cliff face in 1954. The descent offers stunning views of the sheer limestone cliffs plunging into the sapphire sea below.

Planning the wider trip? The Sardegna planning guide covers how to get there, how to move around, where to stay, realistic costs and a day-by-day itinerary that includes Neptune's Grotto.