Imagine if the Grand Canyon were underground—that should give you an idea of what to expect when you enter the Škocjanske Jame (Škocjan Caves). Lonely Planet listed them as one of the top 10 attractions in Eastern Europe. They’re also on the UNESCO World Heritage list and get 100,000 visitors a year. They live up to their reputation by being one of the largest underground canyons in the world with the Reka river still carving through it. At 60 meters wide and 140 meters deep, this canyon is a fraction of the Grand Canyon’s size, but the fact that it’s all underground makes it feel bigger. When you cross the canyon via the narrow Hanke Canal Bridge, you’ll see the roaring river far below. You’ll realize that you could fit a fat 45-story skyscraper in this subterranean world.
The Škocjan underworld is so enormous that a unique ecosystem has evolved here—it’s home to strange blind creatures that have never seen sunlight. The most bizarre one is the proteus. Slovenians informally call it the človeška ribica (human fish). This alien vertebrate is as long as your forearm, has a long tail for swimming, gills, four legs, pigment-free skin, a highly sensitive nose, a sensor for detecting weak electrical fields in the water, and a pair of atrophied lungs and eyes that don’t really work. They’re a weird amphibian that lives almost exclusively in water. Their life cycle is mystifying: they live almost as long as humans, they become sexually mature as teenagers, they have never been seen reproducing in the wild, their babies hatch out of eggs, and they can live up to 10 years without food. It’s one of the most hidden creatures in the Hidden Europe.
About 30 minutes away from the Škocjan Caves is the Postojna Cave, which features perhaps the most thrilling underground train ride on Earth. To help you explore part of the 21-kilometer cave system, an open-air train whisks you through cavern after cavern in what feels like a Disneyland ride. The difference is that everything you see is real! As you zip under narrow openings, you’ll sometimes feel like you need to duck to avoid hitting a stalactite. The ride feels like it’s straight out of Jules Verne’s Journey to the Center of the Earth. The train eventually stops and the one-hour walking tour begins. The tour’s climax is a subterranean chamber called the Concert Hall, which holds music events that can accommodate an audience of 10,000.
Slovenia’s third amazing cave has a gaping mouth so enormous that a castle is embedded in it! The invincible and surreal Predjama Castle is straight out of one of Tolkien’s visions. A medieval Robin Hood, Erazem Lueger, used this fantasy fortress as his hideout. When Austrian soldiers laid siege for months, he tossed fresh cherries and flowers on them to prove that he had a secret magical portal that let him come and go at will. His fun ended when he was sitting on the toilet and an Austrian cannonball landed on him.
This is an excerpt of The Hidden Europe: What Eastern Europeans Can Teach Us.