Grotta di Nettuno, or Neptune’s Grotto, is a sea cave on the cliffs of Capo Caccia, near Alghero in north-west Sardinia. Inside, a guided visit passes stalactites, stalagmites, large rock columns and a still underground lake. The cave formed about two million years ago, and its unusual acoustics add to the quiet atmosphere. You can arrive by boat from Alghero or Cala Dragunara, or reach the entrance by descending the cliff staircase. Only a short section of the extensive cave complex is open to explore.
A sea cave on Capo Caccia
Grotta di Nettuno lies in the cliffs of Capo Caccia, about 25 kilometres from Alghero. The cave is part of the Capo Caccia-Isola Piana Marine Protected Area and Porto Conte Park. Its origins date back about two million years, and its location makes the approach part of the visit: the entrance opens onto the coast beneath the headland.
The cave takes its name from Neptune, the Roman god of the sea. It is an extensive system, but visitors explore only a few hundred metres. That accessible stretch contains the formations and underground water that make the grotto a distinctive stop on Sardinia’s north-west coast.
What you see underground
Inside, stalactites and stalagmites rise through the chambers, alongside massive columns and other irregular rock formations. Their shapes developed over a very long period, and the contrast between the stone and the still water gives the route a different feel from the exposed cliffs outside.
An underground lake is among the cave’s main sights. The water also contributes to the grotto’s notable acoustics. A guided visit takes you through the accessible chambers, with commentary available in multiple languages. The tour gives context to the formations as you move through this section of the larger cave complex.
Arriving by boat or on foot
Boat excursions run to the grotto from Alghero’s port and from Cala Dragunara. The journey from Alghero takes about 30 to 40 minutes, followed by a walkway to the entrance where passengers disembark. This route approaches the cave from the sea and avoids the steep staircase from the road.
You can also reach the entrance overland by descending the Escala del Cabirol, a staircase cut into the cliff at Capo Caccia. The descent is long, and the return means climbing back up, so consider that before choosing the land route, particularly if travelling with young children. Visitors sensitive to heat can plan for the morning, when the path down is shaded.
FAQ
How do you get to Grotta di Nettuno?
Take an excursion boat from Alghero or Cala Dragunara, or reach the cave by land via the Escala del Cabirol staircase on Capo Caccia.
How long is the boat trip from Alghero?
The boat journey takes about 30 to 40 minutes. From the landing point, a walkway leads to the cave entrance.
How much of the cave can you visit?
The cave system extends for more than four kilometres, but visitors can explore only a few hundred metres.
What can you see inside Grotta di Nettuno?
The accessible route includes stalactites, stalagmites, large rock columns and an underground lake. Guided visits include commentary in multiple languages.
