Škocjan Caves

Listed by UNESCO in 1986 and designated Ramsar wetlands of international importance in 1999, with the underground stream of the Reka, this forms one of the longest karst underground wetlands in Europe. The explored length is 6,200 metres, formed in a 300-metre thickness of Cretaceous and Paleocene limestone. At the Big Collapse Doline the Reka drops out of sight and runs underground for thirty-four kilometres before resurfacing near Monfalcone. Slovenia established a regional park and managing agency to protect the area after independence.