Other than the yellow glow of the old-fashioned torches in our hands, there are no lights. We walk in single file through the darkness, the silence broken only by the sounds of our rubber-booted footsteps and distant, dripping water. The damp, uneven ground demands a good part of my attention. As I regularly scan the floor with my light, I spot several pieces of bone and a large tooth embedded in the stone beneath my feet. We pass a large jawbone lodged in the rock, then pause beside a jumbled pile of bones at the end of the passage.
We are in the Medvedji rov, or ‘Bear Tunnel’, in Križna Jama – Cross Cave – about 50km south of Ljubljana, Slovenia. We’re looking at the remains of a cave bear that went extinct about 24,000 years ago.
My partner Jacint and I were travelling with my sister and nephew. We’d based ourselves at a small and friendly campsite, located about half an hour from the famously picturesque Lake Bled. After a couple of days spent hiking, our attention shifted towards Slovenia’s eminent subterranean world. There are more than a thousand known caves in Slovenia, of which 22 are open to visitors. With its promised bear remains, Križna Jama got my ten-year-old nephew’s vote for our first Slovenian cave experience.
Accompanied by a Dutch couple, the four of us were kitted out with almost identical pairs of wellies and vintage-looking torches before following an overgrown path among tall rocks to reach the iron-grated opening of the cave.
Inside, we continue in single file, stopping frequently to observe stalactites and stalagmites. The path we follow is unpaved and marked sporadically with tape. There are no lights other than the torches we carry. Being responsible for what we can see gives us an experience that fully-lit show caves can never provide. And more importantly, the lack of infrastructure preserves and protects this fragile cave system.
Not too far from the entrance, the wall is decorated with signatures left by the explorers who first ventured into the cave. Some signatures date back as far as the 16th century. However, fragments of pottery that have been found relatively close to the entrance suggests that the cave was known and used long before that.
But most significantly, it provided shelter and a place to make a den and hibernate for cave bears. This prehistoric species of bear (Ursus Ingressus) lived in Europe and Asia from around 50,000 to 24,000 years ago. They were larger than modern day brown bears but had a similar skeletal structure. Despite their notable size, the cave bear lived almost entirely on a plant-based diet.
Remains of cave bears have been discovered in various caves in Europe, and in some places – including Križna Jama – a significant number of bones were also found. An enormous skull displayed in a glass cabinet in the main passage is the first example we see. To help comprehend its size, a noticeably smaller and more recent brown bear’s skull is placed on top of the cabinet.
As we progress through the Bear Tunnel, our guide draws our attention to several smooth, almost shiny patches on the wall. These well-worn marks were created by heavy bodies rubbing against the wall as ‘adventurous’ bears ventured deep into the pitch-dark cave to find the perfect spot to spend the winter months undisturbed. Staying close to the wall not only helped them to navigate in the dark but also left a scent on the rocks, thereby marking the route for other bears to follow, as well as helping them find their way back to the entrance. But the great number of bones indicates that not all of them made it out in the spring. Some may have died from old age or illness. However, most would have died of malnutrition. In fact, loss of vegetation meant that food became increasingly scarce, so much so that it led to the cave bear’s extinction during the last Ice Age.
Some 2,000 bones were found in this cave within four days of the discovery of the very first bone in 1878. Two full skeletons were assembled and exhibited in the Natural History Museum in Vienna. Even more interestingly, bones thought to be between 24.000 and 50,000 years old continue to surface as the rock erodes. We spot fragments of bones in numerous places as we look around. Many of these have been recorded and studied but left in the cave, where the constant temperature and stable humidity help to preserve them.
It is probably the closest we’ll ever get to prehistoric remains without a glass panel separating us. For a true hands-on experience, our guide entrusts my nephew with a large molar tooth, placing it into his outstretched palm. He has always been fascinated by fossils and minerals, but after careful observation he hands it back and entertains himself by identifying various other fragments of bones near us. He spots not only the remains of dead animals but also a tiny white creature, hardly bigger than a speck, that moves ever so slowly across a wet rock. It’s one of 60 species of organisms that have so far been discovered in the cave. Bigger (and easier-to-see) animals such as the lesser horseshoe bat also frequent the cave.
Before we return to the main passage, our guide suggests that we switch off the torches and let the complete darkness envelop us. We stand in silence for an eerie minute as only the sound of our breathing breaks the stillness. It’s an experience that you can only get deep inside a cave such as this. It feels weirdly tranquil yet scary at the same time, and we are all happy to switch the lights back on.
Križna Jama is noted not only for the astonishing number of bones that were discovered and continued to be found there, but also for a chain of spectacular underground lakes. At nearly 9km long, this cave system is claimed to be one of the longest caves with subterranean lakes.
Before we explored the Bear Tunnel, we followed the main passage to the first lake, where we boarded a rubber boat. The surface of the water is only disturbed by the paddle, and small ripples brush the boat as we slowly make our way to the far end of the lake. There we make a U-turn, returning to dock in the exact same spot where we boarded ten minutes previously.
The real adventure would have been to embark on one of the extended tours that navigate across a series of underground lakes. However, annual visitor numbers on the 4-hour tour are limited to just 1,000 people. And only a fraction of that number are allowed to go deeper, on an even more impressive 7-hour tour, which is only possible during the winter months when the water level is stable. Sadly, we were not organised enough to book a tour months in advance. We are simply left to imagine that these lakes are just as spectacular as they are described on various websites – though the prospect of spending several hours underground in a small dinghy also fills me with some trepidation. I am cold enough already.
Our small group slowly makes its way back to the entrance, where we are greeted with the warmth of the late August sun as we emerge from the cave. Our eyes need a couple of minutes to adjust to the bright daylight. We hand the wellies and torches back, then buy an obligatory fridge magnet for my nephew. Chilled to the bone, we only shed a couple of layers as we make plans for the rest of the afternoon during a late picnic lunch. My frozen fingers, which kept a firm grip on the torch for two hours, take a while longer to warm up. But as we drive away, we talk animatedly about the wonderful underground world we’ve been fortunate enough to experience. I make a mental note to check the calendar on the cave’s website. Perhaps we could book the longer tour to explore the chain of subterranean lakes next year – I’ll just be sure to bring warmer clothes and a pair of gloves!
