Tucked beneath sheer limestone cliffs, this gorgeous mountain spring is the final outflow point for Italy's largest underground river system. Water percolating through the countless fissures and sinkholes in the Supramonte's high country eventually gathers here and flows out to join the Cedrino river. The spring is beautiful any time, but try to catch it around 1pm when the sun passes directly overhead, turning the water brilliant green. Afterwards, the adjacent tree-shaded park is perfect for a picnic or an afternoon swim in the reservoir.
Scientists have only recently begun unravelling Su Gologone's mysteries. In a 1999 experiment designed to trace the flow of water through the Supramonte, researchers injected fluorescent dye into the waters of S'Edera cave near the mountain village of Urzulei. After waiting nearly a month, they discovered the dye finally flowing out right here at Su Gologone. The spring's normal flow has been measured at 500L per second, though it's estimated to increase to 10,000L per second during rainy periods. And the total volume of the Supramonte's underground water system is estimated to be about 100 million cu metres. Any way you slice it, there's a lot of water in there: in 2010 Italian diver Alberto Cavedon explored the spring to a depth of 135m – but still didn't reach the bottom!
To get here from Oliena, follow the SP46 east 6km towards Dorgali, then turn right following signs for Su Gologone until the road dead ends into a parking lot.