Grotte Is Zuddas, Natural cave system in Santadi, Italy

Grotte Is Zuddas runs about 1,650 metres through dolomite of the Monte Meana; visitors follow a 500-metre underground loop through electrically lit halls such as the Sala della Collata, Sala della Medusa, Sala delle Erosioni and Sala dell'Organo. Besides stalactites, stalagmites and columns, the route shows tubular stalactites, canopies, moonmilk and needle-shaped aragonite crystals, the so-called cave flowers, concentrated in the Sala delle Eccentriche.

The limestone rock formations developed through geological processes over millions of years, while in the 1960s the site operated as a stone quarry for alabaster extraction. This dual past shapes how the cave appears today.

The cave's name, Is Zuddas, comes from the Sardinian term for the juniper shrubs that grow around the Monte Meana entrance. Guides usually lead tours in Italian, and the cooperative running the site is made up mostly of local cavers from Santadi.

The visit runs along about 500 metres of secured, electrically lit paths through several halls, from the Sala della Collata to the Sala dell'Eccentriche. The cave is closed from 1 November to the end of February, except 19 December to 7 January. Photography and filming without flash or tripod are allowed; tours are usually given in Italian.

This cave contains an extraordinary concentration of aragonite formations that develop in multiple directions, seeming to defy gravity. These unusual patterns form because of very specific geological conditions that are particularly strong in this location.