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We departed the Postojna Cave train inside the hollowed earth and walked in the darkness as our eyes adjusted to the dim lighting. Outside, the Slovenian summer sun was already hot, but 2km deep in the Postojna Cave, the damp air cooled our skin and clung to our clothes. As we stood in the vast space, known as the Great Mountain, we were beginning to see our surroundings more clearly…and we were in awe. This was just the beginning of our incredible day visiting Postojna Cave and Predjama Castle in Slovenia.
Slovenia Caves: Postojna Formation
The massive 24km passageway – of which we would walk 1.5km on the Postojna Cave Tour – was formed millions of years ago by the underground Pivka River; the water dissolving the limestone and creating open space below the earth’s surface. In the thousands of years that have passed since the now famous Postojna Cave was created, nature has been slowly, but steadily, decorating the interior with an array of rock formations. The stalactites and stalagmites created by water dripping through the earth’s crevices are stacked from the floor and dangling from the ceiling like petrified icicles – creating a beautiful, yet surreal, scene – and make visiting Postojna Cave one the best things to do in Slovenia.
Visiting Postojna Caves, Slovenia
Postojna Cave Slovenia Tour
Although we are not the first or among the few to have seen the inside of Postojna Caves (the Slovenia caves have been open to the public since 1819 and as of 2021 have welcomed nearly 40 million visitors), we felt like explorers discovering the cavernous corridors. We were guided from the Great Mountain across the Russian Bridge into the Beautiful Caves, so aptly named for the fact that it is, indeed, the most beautiful part of the underground Postojna Cave Slovenia tour.
Postojna Cave Rooms
On our Postojna Cave Tour, we walked through three distinct sections (seeing clearly why these are the best caves in Slovenia), which felt like walking through galleries at an art museum. In the Spaghetti Hall, thousands of thin, white stalactites hang from the top of the Postojna Cave, which to us looked like a shreds of cheese dangling from a giant cheese grater. In the next gallery, the White Hall, enormous, white stalagmites stand like dripping candles; the rocks’ pearly appearance is obtained from concentrated calcium carbonate. In the Red Hall, the stalactites and stalagmites are rust colored, attributed to the iron minerals from the soil above.
Famous Postojna Cave Rock Formations
Some stalactites and stalagmites in Postojna Cave are so unique that they’ve been nicknamed. The “Leaning Tower of Pisa” resembles the building it is named after; “Romeo and Juliet” are two, long, skinny columns that have joined into one; the “Organ” looks like an organ perched in the church choir and “Brilliant” looks like an enormous diamond on display (although, we think it looked more like a double-scoop of ice cream!).
Total Darkness In Postojna Caves Slovenia
Throughout Postojna Cave, two other colors appear on the rocks – black and green. Black is a naturally occurring pigment from manganese, but the green is mold. The unnatural lights introduced to the interior of the cave facilitate the growth, which is why lights are used sparingly and camera flashes are prohibited inside Postojna Cave. To show us the true darkness of the cave, at one point on our Postojna Tour, our guide extinguished the lights and we were enveloped in complete blackness.
Postojna Cave Human Fish
Mold, however, isn’t the only thing living in the cave. There are more than 100 species that call Postojna Cave home. Insects and spiders make up the majority of the list, but the most interesting creature to dwell in the cave is the Proteus, also referred to as an Olm, Baby Dragon and, our favorite, Human Fish. The pale pink, salamander-like animal is completely blind, grows to almost 12 inches, lives to be 100 years old and can go without food for 10 years at a time. Since these creatures would be fairly difficult to find naturally within the cave, a large aquarium holding Postojna Cave Human Fish is located inside the cave so that we could get an up-close view. Our visit happened to coincide with a rare event: the birth of baby Proteus. Although they weren’t yet ready to be formally introduced to Postojna Cave visitors, we could watch their movements on a video screen.
Postojna Cave Concert Hall
The last ‘room’ on our Postojna Tour before boarding the train to exit the cave was the Concert Hall. The room holds an echo for five seconds and has been used as a performance hall by various singing groups – and even an in-cave basketball event! Also in the room is the world’s oldest underground post office, which has been post marking parcels since 1899.
Our tour inside Postojna Cave lasted about an hour and a half, but with the “Full Park Experience” ticket, there was more to see. We had access to the on-site, underground zoo and expo center – as well as the nearby Predjama Castle. At the end of our Postojna Cave Tour, it seemed our day was only beginning!
Visiting Vivarium Proteus and Expo Center Postojna
The underground zoo, Vivarium Proteus, features the insects and other creatures that inhabit the Postojna Cave. In 1831, the first cave beetle was discovered and it launched a new branch of biology, known as Speleobiology. A small laboratory and display exhibits are located within Vivarium Proteus.
To gain a better understanding of the history of Postojna Cave, we visited the expo center. Informative and interesting displays of the creation of the cave, as well as the story of the discovery and promotion of the cave as a tourist sight, were highlighted. Particularly intriguing were the details of how Postojna Cave was originally equipped to handle the visitors, including how the cave was lit and the development of the interior railway, which has been in existence since 1872.
Lunch At Postojna Restaurant: Proteus
The Predjama Castle was the final site we would visit, but the castle is actually about 10km from Postojna Cave. Before hopping on one of the free shuttles that run guests between Postojna Cave and Predjama Castle, we detoured 1km from the cave to the town of Postojna for a lunch fit for royalty at Proteus Restaurant.
The bright and atmospheric Postojna restaurant serves first class cuisine. Our decadent, two-hour, five-course lunch – of which the highlights were baked octopus in a tomato sauce and glazed lambchops – was complimented with delicious Slovenian wine.
Visiting Predjama Castle Slovenia
When we arrived at Predjama Castle in mid-afternoon, we leisurely wandered the grounds before entering the famous Slovenian cave castle. An impressive sight, the stunning Predjama Castle is perched in the middle of a 400-foot cliff. Built 800 years ago during the Middle Ages, Predjama Castle was constructed to incorporate a natural cave, which provided secret passageways, a natural water source and hidden rooms. The unique ‘Castle in a Cave’ is unlike any other castle we have ever visited.
Predjama Castle Tour
When we were ready to tour the Predjama Castle inside, we moved at our own pace through nearly every room soaking up the Predjama Castle history. A free audio guide (offered in multiple languages) is included with the Predjama Castle admission ticket. In each room of Predjama Castle Slovenia, we were provided a bit of history about how the space was used – from the dungeon to the dining room to the chapel – and even toured the Predjama Castle interior built into the natural cave. Visiting Predjama Castle was the best way to end our Postojna day trip from Ljubljana!
Tips For Visiting Postojna Cave and Predjama Castle
Official Site: Postojnska Jama
Postojna Cave Price: Prices vary depending on which package is purchased. Tickets to Postojna Cave start at 25 euro (at time of writing); however, there are discounts for purchasing a single ticket to multiple attractions.
Postojna Cave Tickets: Postojnska Jama Ticket Page
Getting from Ljubljana to Postojna Caves: Directions and Transportation Information
With the caves near Ljubljana, it is fairly simple to make a day trip from Ljubljana to Postojna. Even more convenient is that there is a public bus from Ljubljana to Postojna Caves operated by Arriva. Search for the Ljubljana to Postojna Caves bus on the online schedule from Ljubljana (Ljubljana AP) to Postojna Cave (Postojnska Jama). Cost is €6 each way.
Hotel Postojna Jama: The on-site hotel, Hotel Jama, is located just 100 meters from the cave and is highly rated in customer reviews. However, there are other options for hotels in Postojna, which you can search on Booking.com.
What to Wear: The temperature inside the caves is about 46-50˚F year-round. I felt silly carrying a fleece jacket with me in the middle of August, but I was happy to have it after entering the cave! They also rent jackets at the cave entrance for those who come unprepared. Also, make sure you wear good shoes, as the interior of the cave can be slippery. I wore my Columbia shoes, which are great for travel – and Kris wore his Merrells.
Ljubljana Caves Tour
While we made our own way from Ljubljana to the caves, there are ample options of Slovenia Cave Tours departing from Ljubljana. If you would rather have a guided tour from the city, check the highly-rated Postojna Cave Tour from Ljubljana on Viator.
Trying to decide between visiting Postojna or Skocjan Caves? We loved both! Read about our visit to Skocjan Caves here!
Top Tips For Your Trip To Slovenia
We have a few additional tips for your trip to Slovenia!
Where To Stay In Ljubljana
Guests staying overnight in Ljubljana have several options when it comes to accommodations.
During our visits to Ljubljana, we stay in Airbnb Apartments. (Not already a member of Airbnb? Use this link to create an account and save money on your first stay!) We find that Ljubljana holiday apartments often have more space than hotels – and the added benefit of a kitchen. And, they are usually more affordable than hotels, too.
However, for those who prefer staying in traditional accommodations, there are many hotels to choose from in – or close to – the city center. Check out these top-rated hotels (based on guest reviews!) for your upcoming trip: Hotel Cubo, Adora Hotel or the classy Grand Hotel Union.
For a really unique stay, visitors should check out Hostel Celica – a former prison-turned-hostel that features decor by local artists and a jovial atmosphere.
What To Pack For Slovenia
We offer a few of our best Packing Hacks for your visit to Ljubljana!
Ljubljana is a walkable city…but only if you have the right travel shoes! Don’t forget to pack a pair of lightweight and comfortable walking shoes for your trip. I (Sarah) have traveled with these shoes by Columbia and Reef. Kris prefers wearing these shoes by Merrell.
We’re certain you’ll be snapping tons of photos during your trip. Rather than relying on your mobile phone to capture the sights, upgrade to an actual camera for higher quality photos. We travel with a Canon Rebel (which takes amazing photos, but can be a bit clunky) and a Canon PowerShot ELPH (which takes beautiful pictures, is slim and lightweight).
Map, Guidebook & Day Pack
It’s easy to get turned around in any foreign city…and especially Ljubljana! Make sure to have a good city map and/or guidebook before arriving. You will also want a great day bag to organize and secure all your essential everyday travel items!
We think travel insurance is essential! If you haven’t already obtained travel insurance for your trip, travel protected with World Nomads.
We want to know: Have you visited Postojna Cave and Predjama Castle? What were the highlights for you? What other caves have you visited? Tell us in the comments!
A special thanks to Postojnska Jama for hosting us; as always, the opinions expressed in this post are our own.
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