Sloveniaunderground
Slovenia has more than 14,000 registered caves. This independent guide covers the ones that are open to visitors and the karst landscape around them.
Explore the cavesThe best-known caves
Twelve caves in Slovenia are equipped for visitors. These eight are the most visited.
Postojna Cave
24 km of passages and an underground railway
Škocjan Caves
A UNESCO-listed underground canyon
Predjama Castle
A fortress in the mouth of a cave
Križna jama
By boat across underground lakes
Planina Cave
Where two underground rivers meet
Vilenica Cave
Europe's oldest show cave
Županova jama
Seven halls near Ljubljana
Snežna jama
An ice cave high on Mount Raduha
caves registered in the national cave register, with more added every year
of Slovenia's surface is karst, a landscape shaped by dissolving limestone
of known passages in Postojna Cave, Slovenia's best-known cave system
The word karst comes from the Kras plateau above Trieste. Geologists took the terms doline, polje and ponor from this region as well.
A railway into the mountain
Postojna Cave has been receiving visitors since 1819, and since 1872 it has carried them in by train. The ride covers roughly 3.7 km of the cave before a walk through halls of dripstone known as the Great Mountain and the Beautiful Caves.
The cave's symbol is the Brilliant, a five-metre stalagmite of white calcite. The cave is also home to the olm, a pale, blind salamander that can live for a century.
The canyon under the Karst
At Škocjan the Reka river sinks into one of the largest known underground canyons. The path crosses it on the Cerkvenik Bridge, some 45 metres above the water.
UNESCO inscribed the Škocjan Caves on the World Heritage List in 1986. The river flows underground for about 34 km and surfaces near the Adriatic coast as the Timavo.
A lake that comes and goes
Karst also shapes the surface. Lake Cerknica fills a whole valley in a wet autumn and can be gone by midsummer, when it drains through swallow holes in its bed. Nearby, the roof of a cave has collapsed to leave two natural bridges standing over the Rak stream.
Both places are free to visit and have marked walking trails.
The human fish
Slovenes call the olm človeška ribica, the human fish, for its skin the colour of pale flesh. It breathes through feathery gills, keeps its larval form for life and can go years without food.
The Dinaric karst is among the richest places on Earth for cave-adapted animals. The first cave beetle known to science was collected in Postojna in 1831.
Slovenia's caves in figures
Planning a visit
Most of the large caves are within an hour of each other, between Ljubljana and the coast.
Common questions
The FAQ covers which cave to choose, how cold it is inside and whether you need to book.