Inside Postojna Cave

Like most caves, Slovenia’s Postojna Cave is cold, dark, and damp. But unlike typical caves, it’s also beautiful, at times incredible, and even quite magical.

Postojna Cave is a short 40-minute drive from Ljubljana and is one of the must-sees in Slovenia and this general area of Europe. I confess that visiting a cave in Eastern Europe has not been in my travel radar at all, so when photos of glistening stalagmites came up in my research, I was pleasantly surprised.

We had two days in Ljubljana; we dedicated Day 1 walking around Old Town, and for Day 2, we booked a combo trip through to see Postojna Cave and afterwards, Predjema Castle.

As someone who has never been to a cave before, the photos got me pretty excited—large cave halls, shimmering stalagmites and stalactites, and most especially, photos of the strange-looking human fish (or olm) which is a specie endemic to the cave.

The human fish (also known as olm) is endemic to the cave system. (Photo credit: C. Mlinar for Postojna Cave Archives)

We met our tour group at 8:30AM at Old Town and we were lined at the cave’s entrance well before 10:00AM for the first tour of the day.

Upon entry:

A few steps into the cave and we immediately felt the temperature drop. It was 29ºC outside the morning we visited but inside, it was a cool 10ºC which is apparently the constant temperature in the caves year-round. We were ushered towards a well-lit platform where we boarded the “cave train”—a series of two-seater carriages linked together to form a train.  After a few reminders for safety (do not stand up, lean out, and jump on or off during the train ride), we were on our way.

The first 2 km:

The train ride took us deep into the cave system. At first, we went through artificial tunnels but before long we were flying through natural passageways and jagged rocks surrounded us in all directions. The cave train went through some cramped, dark tunnels with very low ceilings that will make you duck in your seat. But it also took us through cave halls so spacious and so well-lit that we could easily spot stunning rock formations on display.


Aboard the “train” going deeper into the cave through (at times really narrow) tunnels


Stalagmites take 30 years to grow 1mm and this towering stalagmite is one of possibly thousands inside the cave.


Left: A lone stalactite hanging from the ceiling; Right: A thick stalagmite almost forming a wall-like structure.

Seeing the cave on foot:

After 2km, we got off to continue the tour on foot. At a large cave hall, all visitors dispersed into language groups. My husband and I went to stand by the large sign that had “ENGLISH” on it and waited for our tour guide with our fellow English-speakers.

For the next hour, our tour guide took us through the different “galleries” just like in modern museums. We stopped many times to talk about the cave’s history and identify the most beautiful formations: there were enormous pillars, fragile-looking spaghetti-shaped stalactites, paper-thin curtains made of rock, and cascading rocks that look like waterfalls.

Considering that it takes 30 years to produce 1mm of stalactite, it’s hard not to be overwhelmed with awe while walking the caverns.

My four favourite parts of the tour:

1. No slip.  Even if the cave is dark and damp, walking is very safe. According to our guide, a special kind of sand was mixed into the material used for the walkways’ flooring so there is no need to worry about slipping even in the steeper areas.

2. Absolute darkness.  At one point in the tour, all the lights of the cave were turned off for a few seconds to show the visitors the natural cave environment. Without the artificial lights, the cave is absolutely, indubitably pitch-black.

3. The Brilliant.  Postojna Cave’s crowning glory is the bright white, five-metre high stalagmite called “Brilliant”. It is absolutely beautiful and it glistened as I moved around it.

4. The human fish.  Towards the end of the tour, we got to see the human fish inside an aquarium. Typically shy, we were lucky that one olm was in clear view and not hinding under rocks that morning.  No eyes, no pigment, eel-like appearance but with front and hind legs—it’s a strange-looking creature.  Legends have it that it’s the larvae of the dragon that lives in Ljubljanica River.


The walkway that visitors take throughout the cave


The tour groups gathered in an immense cavern while waiting for the tour guides.


Enormous pillars that took millions of years to form.


The “Brilliant,” Postojna Cave’s crowning glory, is whitest stalagmite in the entire cave system.


The Brilliant is especially beautiful when seen in context of the ‘baroque’ pillar that stands to its left, and the ‘waterfall’ stalactites as its background.


Beautiful cascading stalactites.


Strange shapes and shadows make for eerie formations.


Like candlewax dripping through millions of years.

Ending with echoes:

Our walking tour ended at the Concert Hall—the most expansive cave in the system.  Large enough to comfortably seat over 10,000 people, it is apparently used as a venue for symphony orchestras or other musical performances especially around Christmas.  There was no special event when we visited, but we tested out the acoustics by shouting out ‘hello’ while standing in the middle of the cave.  Five echoed ‘hellos’ later, we found ourselves wishing pretty hard for a musical performance right then and there.


Visitors (right side of the photo) dwarfed by the enormous Concert Hall.



One last shot as the train took us back to the surface.

Some practical points about the cave:

1. The cave is pretty cold at 10C, but aboard the train moving at 13kph, it can get even colder so bundle up.

2. There are mixed directions about photography in the cave. Some signs say ‘no photography’ but the website says ‘visitors are forbidden from taking photographs of cave animals or taking photographs using flash light or photographic tripod.’ I was able to take some photos without flash but without a tripod and given the low light in the cave, I had to really bump up my ISO which led to noise in my photos. (Please do not use your camera if you don’t know how to turn off the flash; the bright light hurts the animals in the cave and also discolours the rocks with algae formation triggered by the light.)

3. Try to stay close to your tour guide as there are a lot of additional things you can discuss with him/her in between ‘stops’ that will help further enrich your experience in Postojna Cave.

4 thoughts

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  2. Dear Jizelle,
    congratulations for your articles and very nice photos from Postojna Cave and Predjama Castle. We are really glad to hear that you had a wonderful time when visiting them. I’m asking you just one thing. We really appreciate if you could change photo credits by the photo of Proteus Anguinus to “photo C. Mlinar for Postojna Cave Archives” (instead of
    Thank you and welcome again!
    Postojnska jama, d.d.
    Sabina Paternost

    • I’ve made the change to the credit. What an amazing photograph! I chose not to take one of the olm because my camera has a red light and I didn’t want it to get disturbed by the light.

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