The Karst is the land between the Trieste Bay and the Vipavska Valley and at the same time it is also the name for all the amazing shapes created by waters in the fusible stone. Picturesque karst phenomena can be found in almost half of the area of Slovenia. Besides more than eight thousand known karst caves and potholes, there are also karst springs and intermittent springs, disappearing lakes, swallets and swallow holes, original karst poljes and apparently dry sinkholes.
At the area of Karst and in the region usually called Notranjska there are the most famous caves in Slovenia: the Postojna Cave which is the most visited cave in Europe, the Škocjan Caves, listed in the world natural heritage at Unesco, the Križna jama Cave with its underground lakes, the oldest tourist cave Vilenica near Lokev and all the caves connected with the Postojna Cave – the Pivka Cave, the Črna jama Cave, the Planinska jama Cave, the Otoška jama Cave, the Cave under Predjama Castle and others. The disappearing Cerknica Lake is of karst nature and when it is full of water it is also the largest of Slovenia’s natural lakes. The unusual Divje jezero Lake near Idrija shares the Karst nature; its waters come from an underground gallery of unique depth. The mysterious lives of karst rivers can be seen in the Rakov Škocjan Regional Park. There is a natural teaching trail in that karst valley with natural stony bridges above the river. The Karst Snežnik Plateau is also famous for numerous karst phenomena. Lipica, the cradle of famous white Lipizzaner horses, medieval Štanjel with its castle and Fabiani park and many other cultural, ethnological and culinary specialities attract visitors to the region of Karst.
In the Dolenjska and Bela Krajina regions you can discover the mysteries of karst underground as well. The picturesque Krka River has its karst source in the Krška jama Cave, there are the Želnjske jame Caves near Kočevje which are not deep under the surface and the Ledena jama Cave on Stojna with its ice lake during the whole year. The largest of the karst caves of the Dolenjska Region is the easily accessible Kostanjevica Cave. Besides numerous caves and potholes there are large karst poljes, swallow holes and springs which create the image of the landscape. The beauties of the shallow Karst are presented in the Lahinja Regional Park.
A special value of Slovenia are also the alpine Karst phenomena in the Alps. At Kaninski podi there are potholes considered the deepest in the world and you can view karren, grooves and other surface Karst formations. Another peculiarity of the Slovenian Karst is also the Snežna jama Cave under Raduha which reveals mighty underground halls with ice drip-stones and lakes at the 1556 meters above sea level.
Many other underground experiences can also be found in Slovenia. In Šempeter the Pekel Cave, which boasts the highest underground waterfall in Slovenia, surprises its visitors and in the hilly Haloze near Makole there is the geologically interesting Belojača Cave.