The Bue Marino Cave is one of the main tourist attractions for those who choose to visit the Gulf of Orosei and get to know a little more closely the history and nature of this evocative part of Sardinia. Today, it is part of the second longest karst system in Italy, with an uninterrupted network of underground tunnels stretching for 72 km, from the Supramonte of Urzulei to the crystal-clear waters of Cala Gonone, Dorgali. The cave owes its name to the mammal that frequented and inhabited it until the 1980s, the monk seal, called by the locals "bue marino" (sea ox).

 

The Bue Marino Cave is a complex karst system in its own right, continuously studied not only from a speleological point of view, but also geological and biological. In fact, it is divided into three distinct branches, each several kilometers long: the North Branch, which extends for over 10 km; the Middle Branch, consisting of an underwater tunnel of about 5 km; and the South Branch, currently the only one open to the public, which extends for 8 km and represents the physical connection with the Codula Ilune karst system. It is the latter, in fact, that, connecting four main entrances/caves—Su Palu, Monte Longos, Su Molente, Bue Marino—constitutes the longest underground cavity in Sardinia. One of the exclusive features of the South Branch of Bue Marino is the meeting of sea and river, which occurs about one kilometer deep from the cave entrance, creating landscapes with unique colors.

 

The entire karst system is located within a limestone massif dating back to the Jurassic period, while the dating of the Bue Marino Cave is around 4-6 million years. The cavity appears to have been carved out by a powerful underground river, the Ilune River, which, swollen by its tributaries, managed—and sometimes still manages—to completely flood the tunnel. In fact, it is thanks to the powerful erosive action of fresh water on limestone that, over millennia, the river was able to create such a wide and linear cavity inside the mountain, eventually finding its final outlet to the sea.

 

The numerous and majestic mineral formations found along the path inside the Cave were created thanks to infiltration water, mostly rainwater, when the river fluctuated in level inside the tunnel, both before and after finding its exit to the sea; this means that the cave is still active today, that is, it is still possible to find numerous stalactites with hanging droplets, vast wet flows, pools full of pure and crystalline water, and to observe in the water the concentric circles created by the dripping of rainwater.

 

The Bue Marino Cave represents an important heritage not only from a geo-naturalistic and biological point of view, but also from an archaeological and anthropological one; in fact, on the outer wall of the cave, petroglyphs dating back to the Neolithic-Eneolithic historical period have been found. These rock carvings depict a scene probably linked to worship, as there are various anthropomorphic figures in a praying position arranged around two discs, which could represent solar symbols. The petroglyphs are fundamental evidence that once again confirm the cultural vibrancy and deep knowledge of the territory by ancient man.

 

The cave is accessible by sea from the port of Cala Gonone, and inside the temperature remains constant, between 16° and 18°C. Accompanied by the emerald waters of the sea and then by the calm waters of the river, the visitor will be guided, for the first kilometer of the South Branch, through the Chandeliers Hall, so called because of the formations hanging from the ceiling, the Hall of Mirrors with its spectacular reflections, the Organ Hall and finally the Seal Hall, where in the early 1980s the presence of the last pups of the Mediterranean monk seal was documented.