A view from inside a cave looking out towards a rushing underground river flowing through a rocky passage with moss-covered walls.

CC BY-SA 4.0 • Photo by Falk2 via Wikimedia Commons

Underground river passages

Q: What geological features can visitors expect to see along the trails at Rak Škocjan?

Visitors can explore trails leading to dramatic viewpoints of collapsed dolines, natural stone arches, and the entrances to underground passages. The most iconic sights are the Great and Little Natural Bridges, which were formed by the collapse of cave ceilings.

Q: How does the Rak River behave within the Rak Škocjan valley?

The river is a classic example of karst hydrology, emerging from the Zelške jame caves to meander through the valley before disappearing back into the earth. It is fed by underground springs from the Cerknica plain and Javorniki hills, creating a dynamic cycle of surface and subterranean flow.

Q: What makes Rak Škocjan a suitable destination for photographers and nature lovers?

The area offers captivating views of the lush valley, natural bridges, and the powerful subterranean currents of the Rak River. Interpretive signs along the trails provide insights into the valley’s formation, enhancing the experience for those fascinated by geology and nature.

Q: When is the best time to observe the underground river passages in action?

Adventurous travelers can peer into the caves where the Rak flows in and out, particularly during periods of high water. These times reveal the most powerful subterranean currents, offering a more dramatic view of the river's mysterious path.

Q: Where is the Rak Škocjan valley located and what shapes its landscape?

The valley is located in Slovenia and is shaped by the Rak River, which emerges from underground springs fed by the Cerknica plain and Javorniki hills. The landscape is characterized by karst hydrology features such as sinkholes, natural bridges, and collapsed dolines.

Underground river passages shaping Rak Škocjan valley

#4 of 9 in Rak Škocjan

Where: Rak Škocjan, Notranjska
Directions: Directions

Rakov Škocjan is a narrow, wooded valley in the karst of southwestern Slovenia, and it is one of the best places in the country to see how rivers behave in limestone. The stream that runs through it, the Rak, does not follow an ordinary course. It emerges from underground at the Zelške Caves at the upper end of the valley, flows for a couple of kilometres across the valley floor and then disappears again into the rock at the far end. The Rak is fed by water that has travelled through the karst from the Cerknica plain and the Javorniki hills, so the valley is a short window in a much longer hidden journey.

The landscape is shaped by collapse. Long ago, the roofs of caves in the valley fell in, leaving steep-sided hollows, sinkholes and, in two places, rock arches that are all that remains of the cave ceilings. These are the Natural Bridges, the Little Natural Bridge (Mali Naravni Most) and the much larger Big Natural Bridge (Veliki Naravni Most), and walking under or beside them gives a clear sense of the scale of the original passages. The caves where the Rak enters and leaves the surface are the most direct reminder of the underground river, and dark openings in the rock walls lead back into the system.

Several trails lead through the valley and make a gentle half-day walk. The Educational trail has boards that explain karst processes in simple terms, and viewpoints let you look down into the dolines and across to the arches, including a view of the Big Natural Bridge from the north. The caves and formations include cave halls over fifty metres high, though access to the deeper parts is limited, and you should not enter caves without proper guidance and equipment. The best times are spring and autumn, when the water is high and the valley is green and colourful, while in a dry summer the river may shrink.

The valley is also a protected area with a rich plant and animal life, including bats in the caves and many bird species in the woods. Respect the rules of the regional park, keep to the paths, carry out any rubbish and take care on slippery limestone. The nearby Rakek and Cerknica areas offer food and accommodation, and the valley fits neatly into a trip that includes Lake Cerknica, Postojna Cave and Škocjan Caves.

The underground river passages of Rak Škocjan suit nature lovers, photographers and anyone with an interest in geology. Bring a layer, because the valley is cool and damp even on warm days. Visitors will find that Rak Škocjan’s valley rewards slow walking, and that the Rak River is the thread that ties everything together. It is one of Slovenia’s finest karst landscapes.