The Postojna Caves: an underground world you don’t want to miss

The Postojna Caves are among the most impressive natural wonders that Slovenia has to offer. This 24‑kilometre cave system is the largest accessible cave network in Europe and combines spectacular geological formations with a unique underground train ride. With 200 years of tourism history and rich biodiversity, this underground wonder offers an experience that will make your holiday in Slovenia unforgettable. Descend into a world of ancient stalactites and mysterious amphibians.

What makes the Postojna Caves so special?

Postojna Cave is known as the queen of caves, and that nickname is no exaggeration. The cave system is home to some of the most diverse underground fauna in the world and showcases geological formations that are hundreds of thousands of years old. You will find immense halls here, each with its own character and colour.

The Postojna Caves are one of the top attractions among the sights of Slovenia and attract thousands of visitors from all over the world every year.

The White Hall sparkles like glistening ice thanks to the white limestone. The Red Hall owes its warm colour to the iron in the ground. And then there is the Spaghetti Hall, where curtain‑like formations hang from the ceiling. These natural works of art were created by dripping water that left behind minerals.

The scale of it all is overwhelming. The largest halls are so big that you could fit an entire building inside. The stalactites and stalagmites grow only a millimetre a year, which means that some formations are already millions of years old.

The spectacular guided tour through the caves

Your tour begins with an experience you will not find anywhere else: a train ride through the caves. This iconic ride takes about 10 minutes and takes you deep into the underground world. The train speeds through narrow tunnels where the walls sometimes come very close, until they suddenly open up to reveal enormous chambers.

After the train ride, you continue on foot for about one kilometre along asphalted paths. You walk through different rooms and halls, each with its own atmosphere and special formations. The route is easy to walk and accessible for most visitors.

The full guided tour lasts 90 minutes and covers a total of 5 kilometres. That may sound like a lot, but time flies. There is so much to see that your eyes can barely take it all in. The guide points out special formations and tells you about the history and geology of the caves.

Make sure you wear warm clothing. The temperature in the caves is constantly around 10 degrees Celsius, even in summer. Sturdy shoes are recommended, because although the paths are asphalted, they can be slippery in places due to the moisture.

The mysterious ‘baby dragon’: meet the olm

One of the most remarkable inhabitants of the Postojna Caves is the olm, also known as Proteus. This small amphibian is often affectionately called a ‘baby dragon’ because of its pink skin and elongated body. And it is far from an ordinary creature.

The olm is completely blind and has no pigment in its skin. It lives its entire life in complete darkness and can reach an age of up to 100 years. Even more remarkable: it can survive for years without food by slowing its metabolism down to an extreme degree.

This unique species is found only in the underground waters of the Dinaric karst region. The olm is strictly protected because it does not occur anywhere else on earth. During your visit to the caves you can see these extraordinary animals in the vivarium, where they live in an environment that resembles their natural habitat as closely as possible.

The olm is special not only because of its appearance and lifestyle. It also plays an important role in the cave ecosystem. Scientists study these animals to learn more about evolution and adaptation to extreme environments.

Go deeper and discover more: extra exhibitions and the vivarium

Your visit to the Postojna Caves does not have to end with the cave tour. On the site you will find several exhibitions that deepen your understanding of the karst landscape.

The Expo Cave Karst is an interactive exhibition about the formation of karst landscapes. You will learn how water has shaped the underground world and which processes are still ongoing. The exhibition has won awards for its accessible and engaging presentation.

In the vivarium you get a closer look at the olm and other cave dwellers. The animals live here in conditions that imitate their natural habitat. Information boards tell you about their life cycle, behaviour and the efforts being made to protect them.

For those who have more time, there is also a butterfly exhibition. This combination of attractions makes it easy to spend an entire day on the site without getting bored.

Clear explanations: guided tours in different languages

The Postojna Caves pride themselves on being accessible to visitors from all over the world. Guided tours are offered in Slovenian, English, German and Italian. The guide adapts the language to the composition of the group.

Do you speak another language? Then you can use audio guides in no fewer than 19 languages, including Dutch. You are given headphones and a device that automatically provides information when you reach certain points in the cave.

The audio guide often offers more background stories than the live guide can tell during the walk. You will hear about the discovery of the caves, special events from the past and interesting facts about the geology.

Feel free to bring your own headphones if you prefer. Most audio guides use a standard connection.

Plan your visit: opening times of the Postojna Caves

The Postojna Caves are open all year round, including on public holidays and in bad weather. This makes them a perfect activity if it rains or if you want to plan a visit outside the peak season.

Opening times vary by season. In the summer months there are more tours per day, sometimes until 18:00. In winter there are fewer time slots available, but the caves remain accessible.

Tours start at fixed times throughout the day. It is important to take this into account when planning your visit, as you cannot simply walk in whenever you like. The train departs 15 minutes before the official start time of the tour, so make sure you arrive in good time.

During the high season tours can become fully booked quickly. So plan your visit in advance, especially if you are going in July or August.

Stress‑free entry: ordering tickets and reserving a time slot

Buy your tickets online to avoid disappointment. Via the official website of the Postojna Caves you can reserve a specific time slot. This saves you waiting time and guarantees entry.

The price for adults is around €32.90 for the standard tour. Combination tickets are available if you also want to visit Predjama Castle, an impressive little castle built into a rock face. This combination is popular and offers a discount.

Arrive at least 30 minutes before your reserved time. You need time to park, collect your tickets and walk to the departure point of the train. Late visitors may miss their time slot and then have to wait for a later departure, if there is still space.

Pay attention to the rules in the caves. Do not touch anything, stay on the paths, do not use flash photography and do not leave any rubbish behind. These rules are there to protect this fragile environment for future generations.

A visit to the Postojna Caves combines natural beauty with a touch of excitement. The underground train ride alone makes it worthwhile, but the stunning formations and unique fauna make it one of the highlights of your holiday in Slovenia.