This is one region of Slovenia that you cannot get to know merely superficially. Literally. The beauties that lie hidden below the surface are even more astonishing than those that you can admire above ground in this undulating, largely forested region. Practically every square kilometre conceals one of several thousand karst caves.
Not far from Postojna, the administrative, economic and cultural centre of the region, Postojna Cave has been attracting visitors into its subterranean passages with their breathtaking rock formations for over a hundred years. A special electric train carries visitors on a tour of around five of the cave's total 21 kilometres of passages. The cave is home to the only cave-dwelling vertebrate in Europe, a pale-skinned amphibian popularly known as the 'human fish' (scientific name: Proteus anguinus).
Lovers of subterranean wonders will also be charmed by Križna Jama, a cave near Loško Polje, through which you are carried part of the way by boat. The region's remarkable natural sights, which are also part of the Notranjska Regional Park, include a tall natural bridge in Rakov Škocjan. Just a few kilometres away is yet another phenomenon of the karst world: an intermittent lake. In the months when it is full of water, Lake Cerknica is Slovenia's largest lake. One of the first people in the world to research the phenomenon of the disappearance of the lake's water was the famous Slovene historian Johann Weichard Valvasor. In his work The Glory of the Duchy of Carniola, published in the late 17th century, Valvasor also described an original activity practised by the inhabitants of the Bloke Plateau which had a significant influence on the later development of skiing as a sport. At that time the plateau-dwellers were the only people in central Europe to use skis to walk across snow and zigzag down snow-covered slopes.
The Notranjska-Karst region is an area in which the same river rises to the surface and disappears underground six times, each time with a different name, before finally emerging for the seventh and last time as the Ljubljanica. It rises for the first time in Babno Polje, famous as the place that holds the record for the lowest recorded temperature in Slovenia: minus 35 degrees Celsius.
A prominent feature of the varied and hilly landscape of this region is the karst plateau of Snežnik, which is also the highest peak in southern Slovenia. On its slope stands the beautiful Snežnik Castle, which today houses a museum.
The Military History Park in Pivka offers an insight into the more turbulent periods of the 20th century, with its exhibits of numerous armoured vehicles used by the armies that fought in the two world wars and the former Yugoslav People's Army.
Another of the region's centres is Ilirska Bistrica, which in past centuries was known for its timber industry. The saws were driven by numerous watermills on the river. Today the renovated Hodnik's Mill is open to visitors.