Interview #8 – Spela Borko, Slovenia

“Interview” is caving club “Pod RB” initiative dedicated to discussions with cavers from all around the world. What they share about their life above and under the ground, their caving experience, stories, dreams and future plans you can find in the following lines…

Tell us something about yourself in terms of speleological experience.

I started caving in 2013. Since then, I spend almost all my free time underground. From the first trip on I am writing a “caving log” and up to date I count more than 500 cave visits. Alpine caves attract me from the start, this is the area where I conduct the most exploration, with several one-week trips per year and multitude of one day trips (Slovenia is small, so we are lucky to be able to go caving whenever we have a free day). I organized several expeditions in deep caves on Kanin. We try to minimize the unnecessary weight on the expeditions so I developed caver-friendly dry food packages for deep caving. I am a “spreadsheet freak” so I collect the exploration data for several cave projects. I take part in data management in our society, make maps, write reports, etc. Caves are present also in my professional life: I am a speleobiologist. I did my master thesis on deep cave fauna and for my PhD thesis I explore the biogeography and evolution of subterranean amphipod genus Niphargus.

Usually, the team uses me as a squeeze master. Photo: Matic Di Batista.

When the helmet is too big to pass the squeeze. Photo: Behare Rexhepi.

How you started dealing with speleology and why are you still doing it?

I attended the caving course in 2013, and soon figured out that caving is a perfect combination of physical and mental challenge. I love the excitement of discovering the unknown and pushing the limits of myself. I guess I am more of a “type 2 fun” person: being out of my comfort zone makes me feel alive. I found friends and met my life partner Matic Di Batista underground. Last but not least, only in caves I can get good long sleep and clear my mind of all the surface nonsense.

Matic and I on winter expedition on Kanin. Photo: Jaka Flis.

To which club/organization you feel you belong? Tell us something more about this group of people or organization, something about the main drive behind your activities and projects.

Ljubljana Cave Exploration Society (Društvo za raziskovanje jam Ljubljana, DZRJL) is my family. DZRJL is the oldest caving organization in Slovenia, we are celebrating 110th birthday this year. With exception of the time during 2nd WW, club’s members have been active all this time. As our name tells, our main objective is exploration of caves. An important part of exploration is cave documentation, and nobody escapes making maps and writing reports. We are active in karst conservation and protection, through participation in policy making, public awareness campaigns and cleaning actions of polluted caves. We have more than 100 members, the youngest active caver is 14 and the oldest is 86 years old. We have group meetings every Thursday. We developed an online cave database for Slovenia, We are operating strictly on a voluntary basis, and popular expression to describe our society is “organized anarchy”. One can contact us on fb:, through email or check our webpage

Can you tell us about Kanin, what makes it so special?

Kanin mountains are on the border of Slovenia and Italy, in the western part of Julian Alps. A a limestone massif with highest peak Visoki Kanin at 2587 m asl and the springs located in the Soča valley at 454 m, Kanin offers more than 2 km of elevation distance, so the potential for deep caves is vast: eight out of nine Slovenian -1000 m deep caves are located here. The area is known as Slovenian caving mecca. First Slovenian explorations began in 1963, led by our member Jurij Kunaver. Since then, there have been more than 700 caves registered on Kanin in Slovenian national cave database, with dozens more added each year. Our aim is to connect caves with entrances on highest elevation possible with the resurgences, thus making worlds’ deepest through trip. Idea is far-fetched; however, the existing knowledge tells us it is not impossible.

Map of Kanin with cave entrances (red circles), polygon of important caves (black) and marked two systems that we are aiming to connect. Source:

Kanin is a hollow mountain

Can you tell us more about your favourite cave and how you chose to dedicate your energy there? Share with us more details as depth, length, level of complexity, a brief exploration history,  exploration specifics, major breakthroughs and potential.

Maybe I can tell more about Renejevo brezno-P4 system on Kanin. Both caves were found in 1998: Renejevo brezno was soon pushed to -1250 m, where the sump blocked their way forward, and P4 was abandoned due to tight passages in the first 100 m of depth. At the end of 2014, Renejevo brezno was my first -1000 experience, where I realized other areas are just a playground to practice for the real deal. We found new leads, fossil galleries above the sump. Despite the squeezes, P4 was pushed to -450 m where it narrowed again. The plan was to derig it. On a deriging trip we found a new, parallel pit that again ended with too tight a meander. Wind told us that there is more cave behind, so we dug for two years. Finally, the cave opened and survey data showed that P4 is going towards Renejevo brezno. At the end of 2016 we organized an expedition to connect both caves. However, instead of a connection we found “Echo of the Darkness” -200 m deep pit that led us to the biggest chamber under Kanin – “Infinitum”, and to the depth of 1002 m. I think that this was one of my favorite moments underground. A lot of technical climbing, digging and many unsuccessful trips later, both caves were eventually connected more than one kilometer below the surface (summer 2019).

I should also mention last winter’s expedition, on which I am particularly proud. We had only a one week window of good weather and both entrances to the system were under the snow. We managed to coordinate five teams that were in the system at the same time, two of them did the trough trip. At one point there were 17 cavers in the cave, all of them explored or photographed at depths over 1 km. We had to puzzle out how to transfer sleeping bags between the bivouacs and coordinate the exact timing so the teams would not meet in big pits, falling rocks being real danger there. Not to mention that the connection was not even rigged, so the team that went in through Renejevo brezno had to rely on the P4 team  … 

The System is now 1322 m deep and 12 km long. Over 100 people on more than 180 trips contributed to the exploration. We have multiple open leads towards the valley. I conducted some biological work as well, collected previously unknown species that are in the process of scientific description, and we are participating in the Teatime for Science experiment, where we are analyzing the biological decomposition throughout the Kanin underground. The caves here are cold, deep pits are too often connected with awfully narrow meanders, and breakdowns are common in deeper layers. However, the potential for all types of exploration is limitless.

The photo report of a whole system is available here

Infinitum, the biggest chamber under Kanin. Note the caver on the rope and the bivouac. Photo: Uroš Kunaver.

Odmev temine (The Echo of the Darkness), 200 m deep pit in P4. Photo: Uroš Kunaver.

Schematic representation of Renejevo brezno-P4 System. Detailed map is available here:

What about other favourite regions, caves or areas of interest?

I did some caving and speleobiological work in Balkan countries and I took part in last year’s expedition in Cheve, Mexico, led by Bill Stone. But I prefer to explore in “our garden”, where I have an active role in leading the exploration. Pokljuka plateau, under the mountain Viševnik, Julian Alps, was the first challenge of my generation. We discovered the first entrances to The Pokljuka Ridge System (Sistem Pokljuškega grebena) in 2013 and surveyed 10 km of passages up to this day. For Slovenian karst, with particular geological history and vivid tectonic activity, this is a lot: the longest Slovenian cave has “only” 43 km, and it has been explored for 50 years. We still have unfinished business in Pokljuka, but last year we scooped a new area, gray spot on a caving map -the ridge above the Bohinj Lake (plateau under mountain Rodica, called Planina Poljana). The area is completely overgrown with dwarf pine, but we found more than 30 new entrances and surveyed more than 5 km in one year! The labyrinth of old phreatic tubes some 400 meters under the surface is amazing, pure joy for surveying. Basically, we have more caves open than we can handle 😊.

Borehole in Grvn cave, Planina Poljana, above Bohinj Lake. Cave was discovered in 2019 and is now 407 m deep and 3.5 km long, with countless continuations.

What are your plans on current and future projects?

#kanexit is a buzzword these days (we want to exit Kanin, through the mountain of course). Less than 2 km of air distance is separating the Renejevo brezno-P4 System from the cave that penetrates Kanin massif from the valley (Mala Boka-BC4 System). This summer we had a plan to rig the Brezno pod Velbom-Češka jama system, which is the next deep cave on our way, but both entrances were closed with snow. However, we found a new promising cave just in between “the entrance” and “the exit” systems, which we pushed to -400 m in just a few trips. If the weather conditions will allow, we will organize two winter expeditions into P4, with the aim to push all open leads (mostly technical climbing).

Planina Poljana above Bohinj Lake is a long-term project, where we are learning how to explore the maze of passages, not common for Slovenian caves. Matic is developing the aforementioned online database and I am trying to help with it (not enough though). It is becoming more and more useful for exploration purposes (one can add POI, GPS track, entrance photo, etc.) and mobile app is also under development. I try to spread the word about our exciting subterranean world through lectures, events, and writings. I have to finish my PhD and there is never enough time for everything. When I feel I am drowning in overambitious workload I run underground where, if I may be cheesy, nothing else matters.

Rigging one of the hidden gems of Planina Poljana, “Čudo Kranjske zemlje”. Photo: Matic Di Batista

What is your approach toward attracting new speleologists in terms of preparation and training (examples, duration and accents of training, etc.)? 

We organize one caving course per year, for a maximum of 15 people. The program consists of 1 introductory cave trip, 6 lectures and 6 practical lessons (2 times SRT outside and 4 vertical caves). We have hierarchy inside the club (apprentice caver, independent caver, instructor), but we encourage all active members to help on courses, the leader instructor is merely the one who takes over the organization. However, we advocate that the best way to become a good caver is through caving. We are encouraging newbies to attend “harder” trips, where they get to rig the cave, explore, survey, as soon as possible. If somebody dislikes deep caves – no problem, we have “horizontal”, “biological”, “neoprene”, and “photo” sections as they call themselves, even tourist trips happen now and then. One, two or three participants per generation stay, and become active explorers.

If you have experience with incidents in caves, would you share this with us, so other speleologists can learn from your experience? What would be your advice in case of such incidents?

Luckily, I was never on a trip where a caving rescue would be needed. Probably my worst experience was pneumonia-like illness, combined with hernia, on the depth of 1000 meters, in P4 (Kanin). We were on a 6 days long expedition and I got high fever on the second day. On the exit I was coughing non-stop and I could not bend down to grab my duffle-bag, not to mention crawling through tight meanders. Strong painkillers, stubbornness and trust in the team got me through 10 hours of rope work. It was -15 ˚C outside, and we called the helicopter to help us get off the mountain. I was struggling with rehabilitation of two slipped discs for almost a year. I have been present or involved in some minor accidents (tears, broken metatarsal bones, mild concussion, all because of fallen rocks). Calmness and sober judgement, together with a first aid kit and knowledge to use it are crucial. I learned that we are capable of much more than we think, and that irrational fear is our worst enemy. Fear of objective dangers is good though; I fear water and unstable breakdowns the most. In our case, first can be avoided (winter trips), second is inevitable, but I still do not like them … I encourage bivouacking on longer trips, nobody has sound judgement after 20 hours of active caving.

Copacabana, sump in Renejevo brezno (-1250 m). When the storm hits Kanin, the water rises extremely fast, completely filling the collector within minutes. Photo: Uroš Kunaver

What have you learned through dealing with speleology?

Our limits are only in our minds. And that the cave (almost) never ends, only the cavers wimp. Seriously, we learned that there are almost always signs where to search for the continuation, one just has to pay attention. For example, on Kanin, when some caves seemingly ended, wind and white popcorns on the walls led us to climb and reach hidden windows, to push through the breakdowns. Second, there is no place for soloing underground. A team is more important than an individual, even if it is hard to adjust sometimes.

Wind made popcorn, white harbingers of continuation. Fossil passages above the sump in Renejevo brezno, -1100 m. Photo: Matic Di Batista


When we reached this breakdown in Renejevo brezno from below, we bailed. Several years later we rigged it from above, from P4, and connected the caves approximately 1 km under the surface. Photo: Lojze Blatnik

Would you like to share something more with us?

I want to tell all the female cavers out there that sky is the limit (well, the resurgence in our case). Last fall I organized the all-woman expedition in P4. Five of us went on -1000 m. For five days we were exploring new passages, doing technical climbing, digging, and conducted science. It was amazing experience. If I remember doubters and skepticism when I wanted to do my master thesis on deep cave fauna, or go to Renejevo brezno, I am really proud that our club is pushing the limits also in this area.

Group photo in Infinitum, -960 m (P4, Kanin). Photo: Ester Premate

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