Grotta Zinzulusa

Grotta Zinzulusa opens directly from the Adriatic cliffs at Castro. Its name comes from the local word zinzuli, or rags, evoking the stalactites hanging from the cave roof. The guided route passes through about 150 metres of karst chambers to the Cocito, a pool of layered fresh and salt water.

Why it matters

Zinzulusa is a major anchialine cave: groundwater and seawater form distinct layers, creating an unusual environment for aquatic life. It is among the best-known show caves of southern Europe and has also been studied for its prehistoric remains and distinctive cave fauna. In 1999 the Karst Waters Institute included it among the world's ten most endangered karst systems.

What to notice

The cave's chambers reveal different stages of its formation and later use. Near the entrance, stalactites hang above the small pool called Trabocchetto. Deeper inside, the chamber known as Il Duomo rises to about twenty-five metres; walkways cut during guano extraction in the 1940s remain visible. At the Cocito, cooler fresh water floats above warmer, saltier water. The contrasting layers and the cave's formations make its geology unusually legible.

Context and history

Marine erosion opened the cave in Cretaceous limestone during the Pliocene. Bishop of Castro Msgr. Del Duca described it in a 1793 letter to King Ferdinand IV, and naturalists studied it during the nineteenth century. Excavations have yielded microliths, blades, scrapers, pottery and bone, flint and obsidian tools, showing repeated human use from the Palaeolithic onward. In 1996, a speleodiving campaign mapped about 110 metres of submerged passage beyond the Cocito siphon. Zinzulusa opened to visitors in 1957 and has since functioned as a show cave.