Capo Caccia & Nereo Cave

The cape sets the timetable. It faces the open north-west with nothing in front of it, so Alghero operators watch the forecast and take the cave days as they come; on a settled morning boats run the short distance under the cliffs to Nereo, and on a blown-out one they work sheltered water instead. A few wall sites can be entered from the shore, which is useful for filling a second dive, but the signature diving is boat-based.

What Nereo asks for is order rather than nerve. Operators run it in small groups behind a guide who knows which openings connect, and the sequence matters: with entrances spread between 8 and 33 m, the route is planned to work up towards the shallower exits rather than wander. Redundant lights are expected, and so is the buoyancy to move through a passage without putting a fin into growth that took decades to form. Without cavern training behind you, the walls outside are the better use of the day.

Those wall dives stand up on their own. Punta Cristallo and the falaise are vertical limestone worked as slow drifts with the stone on one shoulder and red gorgonians on the deeper sections, while the pierced islet of Isola Foradada is the easier option, a swim-through at about 15 m that also works as a night dive. The area suits divers who already hold cavern training or want a reason to get it, and photographers after red coral without going technical; anyone content on a wall still gets a full trip out of it if the cave is shut.