Neptune's Grotto

At the foot of the sheer Capo Caccia headland near Alghero, the sea has hollowed one of the Mediterranean's celebrated show caves: Neptune's Grotto, a karst cavern at the waterline where guided paths wind past stalagmite columns rising from the mirror of an interior salt lake. Discovered by local fishermen centuries ago, the cave offers a choice of arrivals that is half the excursion - the boat ride from Alghero's harbour along white limestone cliffs, or the Escala del Cabirol, the 'roe deer's stairway' of 654 steps cut into the cliff face in the 1950s, descending 110 vertical metres with the blue of the Coral Riviera below the handrail the whole way. Inside, the chambers run several hundred metres of lit formations - organ-pipe columns, frozen cascades, the still lake doubling everything - and the guides move groups through on a steady rotation.

What you actually see

• The interior lake - stalagmite columns doubled in still salt water.
• The great columns - organ-pipe formations in the lit main chambers.
• The Escala del Cabirol - the 654-step descent glued to the cliff face.
• Capo Caccia from the sea - the white headland walls on the boat approach.

When to go

May to September for reliable boats and warm returns; the cave closes when swell makes the sea entrance unsafe, so calm-day flexibility beats fixed plans. Shoulder months trade a swimming-warm sea for shorter queues at the stairway.

Honest expectations

Rough seas cancel everything at short notice - check the day's status before committing. The stairway is honest work: 654 steps down means 654 back up in full sun, and vertigo sufferers should take the boat. Interior visits are guided, timed and can feel processed in August; the setting absorbs it.

Nearby

Alghero's Catalan-walled old town, the Porto Conte park headlands and the Coral Riviera beaches.