In the 18th century, a local fisherman from Sardinia spotted an opening in a cliff side while fishing off the coast. The opening, which is generally a meter above sea level unless waters are rough, turned out to be a beautiful grotto featuring an abundance of giant stalactites and stalagmites. Named after the Roman god of the sea, the local legend has since become a tourist attraction.
Within the grotto, tourists can visit a 120-meter-long saltwater lake. The shallow salt lake boasts the same calcic salt structures as the rest of the cave.
The entrance to the cave is accessible by boat when waters are calm, or by car. Those driving to the site park atop the cliff and then climb down steps that were made in 1954 known as escala del cabirol, or "goat steps." The passageways within the cliffs are approximately two and a half miles long, although only the first few hundred meters are open to the public.