Slovenia offers Alpine peaks and charming cities, but one of its most unforgettable adventures lies deep underground. The Postojna Cave system promises a journey into a world of geological wonders, accessible by a unique electric train.
All Aboard the Cave Express
Your adventure
into the heart of the mountain begins not with a strenuous hike, but with a train ride. Postojna Cave is famously the only cave in the world with a double-track railway, a feature that has been delighting visitors for over 140 years. The electric train whisks you more than three kilometres into the subterranean landscape, navigating through tunnels and opening into caverns that offer the first glimpse of the immense scale of this underground world. The ride itself is a highlight, allowing you to soak in the surroundings as you travel deeper into a realm sculpted by water over millions of years. It makes the vast cave system accessible to nearly everyone, including families with young children and those with mobility issues.
A Cathedral of Natural Art
Once you disembark from the train, a guided walk begins through a wonderland of speleothems (cave formations). The sheer variety is astounding. You will wander through chambers that feel as large as cathedrals, past delicate, spaghetti-like stalactites, and alongside formations that resemble giant curtains of stone. The tour guides, who offer commentary in several languages, bring the geology to life. Two formations are particularly famous. The first is 'Brilliant', a stunning, five-metre-tall, bright-white stalagmite that has become a symbol of the cave. The second is the Skyscraper, a towering 16-metre-high stalagmite that showcases the immense timescale on which these natural sculptures are formed. The path is well-maintained and relatively easy to walk, allowing you to focus on the jaw-dropping scenery all around you.
Meet the Legendary 'Baby Dragons'
Postojna Cave is not just a geological marvel; it is also a unique biological habitat. The star resident is the olm, or 'human fish' (Proteus anguinus), an entirely aquatic salamander adapted to a life of complete darkness. These pale, blind creatures can live for up to a century and survive for years without food. Local legend once held that they were the offspring of a dragon that lived deep within the mountain. Towards the end of the tour, you will find a specially designed aquarium where you can see these fascinating animals up close without disturbing them. In 2016, the cave became a global sensation when a clutch of olm eggs hatched in the public aquarium, an extremely rare event that offered new insights into these mysterious 'baby dragons'.
Planning Your Underground Adventure
A visit to Postojna Cave is a seamless experience, but a little planning goes a long way. The entire tour lasts about 90 minutes. It is crucial to dress warmly, regardless of the weather outside. The temperature inside the cave remains a constant 10°C (50°F) yearrdound. Sturdy, closed_toe walking shoes are also essential as the pathways can be damp. It is highly recommended to book your tickets online in advance, especially during the peak summer season, to secure a spot on a tour at your preferred time and in your preferred language. The cave is conveniently located less than an hour's drive from the capital, Ljubljana, and can also be reached by public transport.
Combine It with a Fairytale Castle
Many visitors choose to make a full day of it by combining their cave tour with a visit to the nearby Predjama Castle. Perched dramatically in the mouth of a cave on a 123m high cliff, it is the world's largest cave castle and looks like something straight out of a fantasy film. The castle is famous for its legendary 15th century resident, the robber knight Erazem of Predjama, who used a secret network of cave tunnels to withstand a siege for over a year. Combination tickets are available for both attractions, offering a perfect pairing of natural wonder and medieval history.
