Postojna Cave: a rail journey into the Earth
The chill grabs you the moment you step into the tunnel. It stays at 10°C (50°F) year-round. Then the train jolts forward, picks up speed, and drops you into a world where time is measured in millions of years. White stalactites brush past the cars as cathedral-sized chambers emerge from the shadows. Welcome to the largest show cave in Europe.
Why visit Postojna Cave?
This 24 km (15 mile) underground network was carved by the Pivka river over two million years. Discovered in the 13th century, it has been open to visitors since 1819 and has seen over 39 million people pass through. Slovenia is home to 16,000 karst caves, but this one remains the most impressive for its sheer scale and accessibility.
It is also the only cave in the world with a double-track underground railway. Opened in 1872, the line helped pioneer cave tourism long before electricity arrived in the depths. The current train cars are modern, but the experience feels just as historic.
The visit
The train ride
The tour starts with 3.7 km of track (2.3 miles) covered in about 10 minutes. The train plunges into illuminated galleries, weaving between massive dripstones and passing through chambers of staggering volume. Keep your head down, as the stalactites hang low over the tracks.
The walking tour
After the train, a guide leads you on a 1.5 km walk (0.9 miles) along a concrete path. The route goes through the Concert Hall, which can hold 10,000 people, before stopping at The Brilliant, a 5-meter (16-foot) white stalagmite that has become the symbol of the cave. Photos are allowed, but keep your flash off.
Pro tip: Arrive 30 minutes before the time on your ticket. Boarding starts 15 minutes before departure, and late arrivals have to wait for the next tour.
The olm: the baby dragon of the depths
At the end of the tour, the Vivarium showcases the most famous resident of the cave: the olm, often called the human fish due to its translucent pink skin. This blind amphibian is adapted to total darkness and can survive for ten years without eating. Locals consider them the offspring of the dragons that, according to legend, once lived in these depths.
Know before you go
The constant 10°C (50°F) temperature makes a jacket necessary, even in the middle of summer. The floor is damp in spots, so wear closed-toe, non-slip shoes. The tour lasts 1 hour and 30 minutes, and you cannot leave early. The route is accessible for strollers and visitors with reduced mobility, who can opt to stay on the train for the duration of the trip.
The Predjama Castle, built into a cliff 10 km (6 miles) from the cave, is easy to visit on the same day. A combination ticket helps lower the total cost.
Opening hours
*Information subject to change
I really loved visiting these caves. The entrance fee is inexpensive, and the tour lasts almost two hours. Part of it is done on a little train, then you explore the rest of the caves on foot. Remember to dress warmly because it is pretty chilly inside, and wear good shoes.