Neptune's Grotto

Neptune's Grotto opens at the foot of Capo Caccia, a sheer headland on the coast near Alghero. Its mouth sits barely a metre above the Mediterranean under cliffs about 110 metres high, and that position decides everything about a visit: the cave can only be entered when the sea is calm. Local fishermen are said to have found it in the 18th century, and it has drawn travellers ever since — King Charles Albert of Sardinia came three times, in 1829, 1841 and 1843, and marble plaques inside record his visits. The Victorian travel writer John Warren Tyndale, by contrast, spent a long stay in Alghero and never managed to get in.

Inside, a lit walkway leads through a few hundred metres of a system estimated at around 4 km. The centrepiece is the Lamarmora Lake, a saltwater lake at sea level, roughly 100–120 metres long, with a stalagmite column rising from the water whose top holds cups of fresh drip water — the "holy-water font". Beyond it are the Palace Hall, where calcite columns reach about 9 metres and the vault rises to 18, and the Organ Hall, named for a great column whose flowstone ripples like organ pipes. The Hall of Ruins takes its name from the damage done by souvenir-hunters in the 1800s. Monk seals once used the cave; they have long since disappeared from this coast. Tours are guided, in Italian and English.

Until the mid-20th century the only way in was by boat. The Escala del Cabirol ("goat's stairway"), 654 steps cut into the face of Capo Caccia and designed by the Sardinian architect Antoni Simon Mossa, changed that in the 1950s. The descent is spectacular; the climb back up is the part people remember. The waters around the headland hide many more caves, the largest and best known being the Nereo Cave, a favourite with divers. The grotto itself served as a film set in the summer of 1978, for the Italian fantasy film Island of the Fishmen.

Getting there

The grotto is about 13.5 km from Alghero as the crow flies; Alghero–Fertilia Airport (AHO) is a similar distance, about 13 km. There are two ways in: by road to the car park on Capo Caccia and down the 654 steps, or by boat from the port of Alghero (or from the Dragunara pier at Porto Conte), which runs daily in spring and summer and less often in the rest of the year. Entry depends on the sea: in rough weather the cave closes.