Slovenia Underground Tours: Cave Tours from Ljubljana and Koper

Key Takeaways

• The tours visit Postojna Cave or the UNESCO-listed Škocjan Caves.
• Most leave from Ljubljana. A few leave from Koper and pick up cruise passengers at the port.
• Half-day tours pair the cave with Predjama Castle. Full-day tours add Lake Bled or Piran.
• There are small-group tours and a private option.
• The caves stay cool all year, so bring a jacket even in summer.

Why Go Underground in Slovenia?

Slovenia sits on limestone. Over millions of years, water dissolved the rock and carved out caves, sinkholes and rivers that disappear underground. The Karst region in the southwest gave its name to this kind of landscape all over the world. Slovenia has more than 13,000 registered caves, and new ones are still found.

Postojna Cave is the best known. It has more than 20 kilometers of passages, and the visit starts with a ride on an underground train. The first rails were laid in 1872. Inside you walk past huge halls full of stalactites and stalagmites, and you can see the olm, a blind cave salamander that lives only in this part of Europe.

The Škocjan Caves are different. The Reka River runs through a deep underground canyon, and the walk crosses a bridge high above the water. The caves have been on the UNESCO World Heritage list since 1986.

The trips also show how people lived with the caves. Predjama Castle was built into the mouth of a cave in a high cliff, and it is a stop on most tours in this category.

What These Underground Tours Include

Postojna Cave and Predjama Castle (half day)

This is the most common Slovenia cave tour. You drive from Ljubljana to Postojna, ride the cave train and walk through the cave, then visit Predjama Castle nearby. Some tours pick you up at your hotel, and one includes an audio guide at the castle. It’s a good choice if you only have half a day. If you want to know more before you go, read what to expect at Postojna Cave.

Postojna Cave and Lake Bled (full day)

These tours cover two of the country’s best-known sights in one day. Most also stop at Predjama Castle, and one includes a pletna boat ride to Bled Island. It’s a long day with a lot of driving, but it works well if you have little time in Slovenia. For more options like this, see the other day tours from Ljubljana.

Škocjan Caves and Piran (full day)

These trips go to the Škocjan Caves first and then to Piran on the Adriatic coast. One also stops in Lipica, home of the Lipizzaner horses, and makes a photo stop at Predjama Castle. Pick this one if you want the big underground canyon instead of the cave train.

Postojna Cave, Predjama Castle and Piran (full day)

Here you get the cave, the castle and an afternoon on the coast. One tour includes a guided walk in Piran. If the coast is the part you care about most, browse more Piran tours.

Tours from Koper and the cruise port

Two tours start in Koper and go to Postojna Cave with a stop at Predjama Castle. A third picks up passengers at the port. They are timed for a day in port, so they are a fit for cruise passengers. You’ll find more Koper shore excursions in a separate category.

Group, Small-Group or Private?

Your tour guide or driver handles the transport, tickets and timing. Inside the caves, you join a guided tour led by the cave’s own guides, so the cave visit is the same whichever tour you book. What changes is the ride there and the pace of the day.

• Group tours: a set schedule and a bus or van with other travelers.
• Small-group tours: some are limited to 8 guests, so stops are quicker and the guide has more time for questions.
• Private: one tour to Postojna Cave and Predjama Castle is private, with a slower pace. For more options, see private tours in Slovenia.

There are no self-guided or adventure caving tours in this category. All of them are sightseeing trips on walking paths.

Tips for Choosing a Cave Tour

Postojna or Škocjan?

Postojna is easier: a train takes you deep inside, and the paths are paved. Škocjan is a walk only, with many steps up and down, but the underground canyon is something Postojna doesn’t have. With kids or anyone who finds stairs hard, Postojna is the safer choice.

When to go

The caves are open all year and the weather above ground doesn’t change much inside. Summer is the busiest time, and Postojna gets crowded in July and August. Spring, autumn and winter are quieter. In winter, a cave trip is one of the few things that works well in any weather.

What to bring

• A warm layer. Postojna is about 10°C and Škocjan about 12°C, all year.
• Shoes with good grip. Paths can be wet.
• Water and a snack for full-day tours.

Photo rules differ: Postojna allows photos without flash, while photos are restricted in parts of Škocjan. Check before you go.

Ready to Explore Slovenia’s Caves?

Choose a half-day tour if you want just the cave and Predjama Castle. Choose a full day if you want to add Lake Bled or the coast. Start from Ljubljana or Koper, pick group, small-group or private, and check dates for the tour that fits your trip.

FAQ – Slovenia Underground Tours