Exploring Indonesia’s Hidden Underwater Caves: Expedition Buteng’s Groundbreaking Discoveries

We recently had an exciting opportunity to sit down and speak with Rannva Jøermundsson, a diver and explorer, co-founder of NIXIE Expeditions, who recently led an expedition to explore and map an underwater cave in Indonesia. The focus of the expedition was to study the caves' ecosystems through cutting-edge techniques like metagenomics and environmental DNA (eDNA) sampling. Rannva discusses the exciting discoveries made during the expedition, the challenges of cave exploration, and the vital collaborations with experts and organizations that are helping to advance research and conservation efforts. We hope you enjoy the interview.

IS: Rannva, nice to see you! It’s been a while. Tell our readers who you are and where you are from?

RJ: Great to see you, too! My name is Rannva Jøermundsson, and I’m the Global Head of Sales at Fourth Element. I’m originally from the Faroe Islands, but I’ve been living in the UK for eight years now. I moved here after I got the job with Fourth Element.

Beyond that, I’m a dive instructor, a cave diver, and a rebreather diver. I also do cave exploration and am a member of the Explorer’s Club in New York.

IS: So, tell us about how you got started with diving. Where did the passion come from, and where did you do your first dives?

RJ: It all began when I was 20 and backpacking around Australia. I’d seen Finding Nemo, and there I was by the Great Barrier Reef, so I thought, “Let’s do this!” At the time, I assumed diving would just be one of those bucket list items—do a dive course, tick; go skydiving, tick.

But to be honest, I was terrified of the ocean. I had this irrational fear of stepping on sea urchins or being bitten by a shark. That said, I’d always been fascinated by the sea, growing up near the coast and swimming a lot as a kid.

When I did the course, the pool sessions were fine, but what truly blew my mind was getting to the Great Barrier Reef. Putting on a mask and seeing underwater life for the first time was incredible. The feeling of flying with neutral buoyancy—that was something else entirely. I was hooked. I even spent years after that dreaming about diving, literally. It was love at first breath.

IS: But there was a gap before you got seriously into it, right?

RJ: Yes, there was. But after that first dive, I completely altered my trip around Australia to make it diving-focused.

IS: Where did you train?

RJ: I did my training with Pro Dive Cairns and made it up to Rescue Diver there. Then I headed to Indonesia and did my Divemaster course in Gili Trawangan. Afterward, I returned to the Faroe Islands and started diving there.

IS: What was that like?

RJ: Challenging! My first dry suit dive was… an experience. I had this massive neoprene dry suit meant for men, and it didn’t fit well at all. There was so much extra fabric, and the seals didn’t sit properly. I remember asking a friend, “Is it supposed to feel like this?” He assured me it would be fine. Spoiler—it wasn’t!

During the dive, the suit flooded completely. After about 10–15 minutes, I was freezing and asked if we could surface. My friend thought I was just being dramatic, but when we surfaced and I showed him how much water was in my suit, he finally understood! After that, it was all about gaffer tape, elastic bands, and determination.

IS: Sounds brutal!

RJ: It was. Honestly, I nearly quit diving because of how uncomfortable it was. But I had some amazing friends who kept encouraging me to push through.

IS: What happened next?

RJ: I moved to Denmark to study, and that’s where my diving really took off. I met a friend, Boje, on a dive trip to Egypt. He was doing his instructor course and convinced me to join him.

IS: How was that experience?

RJ: It was a unique course, split between Copenhagen and Oslo. Doing rescue exercises in icy conditions with a heavy-duty dry suit was no joke. I still remember the pain of numb fingers and someone pinching my nose during exercises! But it was rewarding. If you can teach and dive in those conditions, you can handle anything.

IS: That’s impressive! Did you stay in Denmark after that?

RJ: Yes, I stayed and worked with Kingfish in Copenhagen. That was a formative time for me. We had regular diving nights, even in winter. If I wasn’t teaching, I was in the pool practicing or watching others refine their skills.

It was an inclusive environment, and I learned so much. I remember watching divers perfecting techniques like backward swimming or maintaining perfect buoyancy against a wall for an entire dive. It inspired me to keep improving.

IS: That sounds like a great community to grow with.

RJ: It really was. I also met Maria Bollerup there for the first time. I’ll never forget her—wearing a Fourth Element drysuit, teaching these tall, burly guys how to back-kick. I remember thinking, “Wow, I want to be like her someday.”

IS: I had a similar experience when I was doing my Divemaster training. There were all these recreational instructors teaching, but then this cave diver instructor came in to do an assessment. We were all sitting there, like idiots, and he just came in, in perfect trim. He did a mask clearing demo, fin pivots—everything was so precise. I remember thinking, I want to dive like that.

RJ: Yeah, exactly! I remember something similar. We were diving with this guy, Kubi, and he was absolutely incredible—just amazing. I was talking to him today, actually, and told him we were here. He was part of the inspiration. It was seeing divers like that, with more serious approaches, that made me want to up my game.

IS: So that inspired you to start technical diving?

RJ: Yeah, it was a bit random, really. A friend of mine mentioned she was heading to Florida for cave training and that they needed a third for their team. She asked if I wanted to join, and honestly, I’d never seriously considered cave diving before. But I called a friend of mine, Boe, and asked, Should I do cave training? His immediate response was, F** yes!* So I thought, okay, let’s do it.

IS: That’s amazing. When was that?

RJ: It was 2015. I went to Florida and trained with Rasmus Dysted from Denmark—Maria’s husband. He’s been my instructor ever since. He even taught me my IDC and how to become a diving instructor.

IS: Was it in flow caves?

RJ: Yeah, we started in Peacock Springs, which has no flow, but eventually moved on to places like Ginnie Springs. Diving in flow caves is such a sensory overload, but it’s so cool. There was one particular spot—small, narrow, and not very long—I can’t remember the name of it right now, but it was a great experience. We also did the course on sidemount, which was new for me at the time.

IS: How did you end up with Fourth Element?

RJ: That was actually tied into the same trip. We were doing our training right after DEMA. Rasmus was going to DEMA anyway, so he suggested Maria and I come along. We managed to get passes and were the annoying tire-kickers wasting people’s time at the show. But that’s where I met Jim and Paul for the first time, and we established a relationship.

IS: So how did that lead to you joining Fourth Element?

RJ: Kingfish, where I was working, was already a dealer for Fourth Element, so I knew the brand and really liked it. A year later, in 2016, I saw they were hiring for a drysuit repair technician and customer service manager. I had no idea how to repair drysuits, but I thought, I can learn. I really wanted to work for Fourth Element, so I applied anyway. I didn’t get the job because of my lack of technical skills, but they liked my other experience—financial advising, being a flight attendant, customer service—and offered me a role in sales.

IS: That’s impressive!

RJ: Yeah, they started me off as the Scandinavian Accounts Manager, but within two weeks, I was handling all distribution worldwide. It was definitely a baptism by fire, with plenty of mistakes along the way! But I’ve been with them ever since. I started on my birthday, November 28th, and next week will mark my eighth anniversary at Fourth Element.

IS: Congratulations! Let’s talk about your expedition. What’s it called, and how did the idea come about?

RJ: The project is called Expedition Buteng, named after the local regency, Buton Tengah. The locals call it Buteng, so we wanted the name to reflect their culture. It’s a remote area with little tourism, but we saw the potential for eco-tourism through cave diving. The idea started when Robbie Schmittner invited us to the Xunaan Ha expedition in 2021, in Mexico.

IS: What was that expedition about?

RJ: It was cave exploration and water sampling. Robbie has this theory that all the water systems in the Yucatán Peninsula are connected. He wanted to prove that pollutants from pig farms or other sources are running through the aquifer and out to the ocean, where they’re suffocating corals. That gave Maria and me a sense of purpose—using diving for something meaningful.

IS: So that inspired your own expedition?

RJ: Exactly. We combined exploration with science. Maria had been to Indonesia before with Robin Cuesta and Pete Mesley, exploring caves in South Sulawesi. Robin had previously found a promising cave on the island of Pulau Muna, and we decided to return to map and study it. That’s how Expedition Buteng began.

IS: What’s the goal of the project?

RJ: We had several goals: studying the aquifer to assess if the water is drinkable, generating media to promote the area as a cave diving destination, and mapping the caves. Long-term, we aim to conserve the area and achieve UNESCO Geopark accreditation.

IS: Did you achieve those goals?

RJ: Yes, except for the UNESCO accreditation—that’s a long-term project. Our team of 28 included 11 cave divers and seven scientists from Gadjah Mada University in Indonesia. Maria and I acted as the scientists’ extended hands and eyes, collecting samples inside the caves.

IS: And the water was drinkable?

RJ: Yes, it was pristine—no bacteria or DNA detected. However, we found that locals are drilling small wells into the aquifer, which risks saltwater intrusion if it continues unchecked. Education is key to sustainable water use.

IS: What’s next for NIXIE Expeditions?

RJ: Right now, it’s about analyzing our data and turning it into actionable insights. We’re also working with a major global organization to create a five-year plan for conserving the area. And we’ll definitely be going back to continue the work.

IS: So, will you be going back to continue the research?

RJ: I'm definitely going back, although there’s nothing planned just yet. Right now, it's about utilizing the information we've gathered and turning it into something productive. The analysis is still happening over at UGM, and it will take some time for them to process everything and figure out what’s actually there. We believe the final report will be done in about a year.

IS: That sounds like an incredibly in-depth project. Can you share some of the highlights so far?

RJ: One of the most exciting parts was working with Dr. Abdul, a biologist who specializes in metagenomics. We were doing sediment samples to look for bacterial phages, which can actually be used in medicine and medical resources. Dr. Abdul was doing on-site sequencing, which was a huge benefit for the project. To be honest, I don’t fully understand all the scientific details because I’m not a scientist, but it’s been fascinating to watch.

IS: It sounds like there’s a lot of collaboration happening too.

RJ: Exactly. We’ve established a relationship between Copenhagen University and some of the leading experts in metagenomics. UGM is just starting to dive into this field, so they’re supporting each other and learning together. It’s about building bridges and sharing knowledge. We’ve also built strong partnerships with the Marine Genome Project, led by Daniel Ortega from California. He’s one of the first to do eDNA sampling in caves, and now we’re working with him on his projects in Sardinia. In addition, we’ve teamed up with Free Attic, who study Mediterranean sea caves in order to protect them.

IS: It seems like there’s a big focus on collaboration and protection.

RJ: Absolutely. The long-term goal is to work together for a greater purpose, which is protecting these ecosystems. Nothing gets protected unless people understand it, know about it, and see it. That’s why it’s so important to build these relationships, and media plays a huge role in that. We had the wonderful Alex Dawson, who was responsible for both motion and still photography on the project. Rolex, through their Perpetual Planet initiative, was the main supporter, and they are now doing image selection and everything related to that. Alex Dawson’s expertise in both video and stills was invaluable. His ability to switch between the two with ease was incredible—it gave me a renewed respect for cave photography and video. I don’t touch video myself, but watching him work was an eye-opener.

IS: That’s impressive. What about the cave mapping? How long did that take?

RJ: The cave mapping took nearly three weeks. It was a crude process, using L-rods to map the cave, which was more about getting a sense of the volume of the cave and estimating the water volume inside. We also had an Indonesian dry caving team with us—six of the best from Indonesia. They were thorough, poking their heads into every hole they could find. They discovered 22 new caves, five of which they managed to map. They were also searching for potential connections between the caves. The dry caves seem to be starting to move toward each other, crisscrossing at different levels. While we didn’t manage to find a direct connection between the dry caves, I’m confident it’s there. It just needs more exploration.

IS: Who were the sponsors for this project and how did you convince Fourth Element to sponsor you (laughs)?

RJ: Convincing Jim to let me take a month off was the tough part! But we had some amazing sponsors. Fourth Element of course, and XDeep was incredibly supportive, especially with their exploration support program to help share the expedition.

DiveSoft, DAN Europe, and DAN were also on board. DiveSoft helped with analyzers and fluorescent dye, though we couldn’t use the dye because the cave was pure white—would've stained the walls. Seacraft provided scooters, which were essential, especially for some of Alex’s images. Halcyon supported us with regs, stages, and exploration reels.

We used Sidewinders on this trip instead of XCCRs. They're simple and reliable—easy to fix, and we could swap parts between team members. Shearwater was also a big help.

Finally, I would like to thank Rolex and their Perpetual Planet initiative.

IS: Do you have a website for the project?

RJ: Yes, the updates and details are available on www.nixie-expeditions.com.