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 suddenly realize that you could fit a massive 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.