In 2014, five friends, all expert cave divers, excitedly descended into one of the deepest underwater caves in Europe to explore its breathtaking beauty. Confident in their skills, they believed they could navigate several kilometers of narrow and branching passages and emerge successfully on the other side without any trouble.

But unbeknownst to them, not all of them would make it out alive. Everything that would unfold was captured by GoPro cameras mounted on their heads. This is their terrifying true story.

The Plura Cave System, located in Rana, Norway, is considered the deepest underwater cave in Northern Europe. Some parts of the cave reach depths of around 135 meters, and the total length spans approximately 30 kilometers, most of which are submerged underwater. Due to its depth, width, and narrow, complex passages, it resembles a giant underwater maze or puzzle.

Surprisingly, Plura Grotta is a popular destination for thrill-seeking deep cave divers and explorers. There are two main entry points to the cave: one is a descent via the Staget cave, and the other is through a small underwater passage beneath Plura Lake.

Despite the extreme danger of diving in this deep, narrow, and treacherous cave, five friends — Kai Kankanen, Patrick Gronkvist, Jari Huttunen, Vesa Rantanen, and Jari U — were determined to take on the challenge. Their journey began when Patrick, Kai, and another diver, Sammy Paakkarinen, discovered that the two cave systems — Plura Lake and Steinugleflåget — were actually connected.

In September 2013, the three divers, along with a few other professionals, successfully navigated the entire Plura Grotta Cave System, becoming the first people to pass through from one entrance to the other. They entered through Steinugleflåget and exited through Plura Lake.

This remarkable discovery boosted Kai and Patrick’s confidence, and just months later, in February 2014, they decided to return — this time bringing along three more friends: Jari U, Vesa, and Jari Huttunen. But unlike their first attempt, they would reverse the route — entering through Plura Lake and attempting to exit through Steinugleflåget.

On February 5, 2014, the five friends traveled from Finland to Rana, Norway, in a trailer van owned by Jari Huttunen. The van was loaded with cave diving equipment, including underwater scooters, tools, gear, and an abundance of oxygen tanks.

They drove across Finland, through Sweden, and into Norway just to reach Plura Grotta. Throughout the journey, they repeatedly reviewed their plans. The group was not just prepared — they were possibly overprepared. With years of experience and training, they were confident nothing could go wrong.

Diving in cave systems deeper than 40 meters is considered professional technical diving, which requires special training due to its life-threatening risks. Fortunately, all five friends were fully certified CCR (Closed Circuit Rebreather) cave divers, which qualified them to explore underwater caves like Plura Grotta using a specialized oxygen supply system used only by highly trained divers.

They had explored the shallower sections of Plura and Steinugleflåget several times before — except for Jari U, for whom this was a new experience. Despite their intense preparation, the expedition would end in tragedy.

Arriving at Plura Grotta late in the evening, they decided to rest at a nearby farm. The next morning, February 6, the divers awoke early for their exploration. However, it was still deep winter, and the temperature was harsh — dropping below -3°C. The surface of Plura Lake was completely frozen.

Nevertheless, the five pressed on with their plan. To avoid murky water that could hinder visibility, they agreed to split into two batches. First, Patrick and Jari Huttunen would descend, followed by Kai, Jari U, and Vesa.

Their entire dive was expected to last around five hours — if everything went smoothly. But first, Patrick had to create a hole in the ice using a chainsaw to access the lake below. They were already behind schedule, so Huttunen decided it was time to begin the dive.

Everything — from the very first descent to the final moments — was recorded on GoPro cameras attached to their heads. Every move and every looming danger would be captured.

Patrick and Huttunen had to move quickly, as every minute was critical in such a risky environment. Around noon, they entered the freezing lake while the others remained above, preparing their gear. Wearing high-tech diving equipment, the first pair slowly began navigating the icy cave with the help of underwater scooters to conserve energy and speed up movement.

Compared to regular free diving or scuba diving, cave diving at such depths demands precision. To extend their oxygen supply and reduce the production of bubbles that cloud the water, they used Closed Circuit Rebreathers (CCR) — sophisticated masks that recycle the diver’s exhaled carbon dioxide, filter it, and mix it with oxygen from their tanks.

This allowed them to stay underwater longer and minimize risks. They also carried spare rebreathers and extra oxygen tanks in case of equipment failure.

As the pair descended deeper, water pressure increased, and the temperature dropped further. They were not only battling the cold and pressure but also the risk of hypercapnia — carbon dioxide poisoning — which occurs when the diver breathes too rapidly and the system fails to filter out CO₂ efficiently. This can cause a diver to lose consciousness underwater — a nightmare scenario.

After nearly an hour, using their scooters, Patrick and Huttunen reached the deepest section of Plura Grotta. From a depth of 34 meters, they descended into narrower passages around 60 meters deep. Before long, they had reached the deepest part of the cave.

A very narrow tunnel, almost 135 meters below the surface, is considered the most dangerous part of the entire Plura Grotta cave system. Before continuing, Patrick let Huttunen admire the stunning beauty of the cave. While pausing for a bit, the two agreed to switch to their spare rebreathers for the next few minutes.

They were already feeling tired, and the increasing pressure of the water was wearing them down. They decided it was time to ascend from the cave. Technically, the next steps for Patrick and Huttunen should have been relatively easy, as they would simply make a slow ascent toward the Stinog Lefaget cave entrance.

However, before they could reach it, they had to pass through another extremely tight tunnel. Patrick went slightly ahead, monitoring their route. But he soon noticed that Huttunen was no longer behind him. This didn’t alarm him at first, so he waited a while before continuing.

Suddenly, Patrick noticed something strange — Huttunen’s flashlight was moving erratically, a clear signal that something had gone wrong. Patrick rushed back and found Huttunen in panic, desperately struggling. It turned out that the cord of Huttunen’s scooter had gotten wedged between rocks, which caused him to completely panic.

Patrick remained calm and successfully freed the scooter. However, Huttunen had already entered a full-blown panic and was calling for help. Patrick helped him switch between breathing systems, but then Patrick noticed something horrifying — Huttunen was no longer breathing.

In fact, his mask had come off due to his frantic movements. Patrick still tried to save him by inserting a regulator into his mouth. But when he turned it on, water — not oxygen — filled Huttunen’s mouth. It was heartbreaking, but Patrick knew at that moment that Huttunen was dead.

Still, he had no time to mourn. Every second was critical. If he stayed there, he might also lose his life. Patrick knew he had to ascend immediately — but he faced a much bigger problem.

When he checked his dive computer, he was shocked to see that he had to stay there for 400 minutes to decompress properly. That meant every minute spent at depth required 10 minutes of decompression. Patrick couldn’t believe what he was seeing.

Could he really survive nearly 7 hours submerged in ice-cold water, over 100 meters deep? To avoid decompression sickness, Patrick needed to ascend very slowly. But there was another problem: he had already given some of his spare oxygen tanks to Huttunen.

With no other choice, Patrick had to continue and bet everything on whatever little hope he had left.

Meanwhile, the second batch — Kai, Vesa, and Jari U — began their descent, unaware of the tragedy that had occurred. Around 2:00 PM, about two hours after Patrick and Huttunen dove, the trio began the same route from Plura Lake to Stinog Lefaget.

After about an hour, they reached the cave’s deepest part — but then they encountered a problem.

Due to the numerous oxygen tanks left by Patrick and Huttunen blocking the tight passage, Vesa struggled to get through. He had to leave his spare tank behind just to squeeze into the narrow tunnel. Things worsened when his legs got stuck between rocks.

Vesa started panicking, knowing they were behind schedule. Luckily, with help from his friends, he freed himself, and the three continued swimming until they reached the narrowest turn in the cave.

As Vesa ascended, he suddenly heard a familiar sound — a distress signal from a nearby diver. Then, he was shocked to see the lifeless body of Huttunen. Vesa was devastated but knew they had to continue.

But Huttunen’s body was blocking the narrow passage, making it even harder to move forward. Vesa remained calm and decided to remove whatever gear he could to squeeze past Huttunen’s body. But Yari U was not as composed.

Upon seeing their dead friend, Yari U suffered a panic attack. He repeatedly tried switching rebreathers, but his body could no longer handle the shock and stress — he lost consciousness and died underwater.

Kai, watching from a distance, saw everything — Vesa struggling to pass, Huttunen and Yari U both lifeless. Realizing the danger, Kai chose to turn back toward Plura Lake to save himself.

But now he had a new problem — he had no more spare oxygen. He had to balance decompression procedures while managing his limited air supply. According to his calculations, he might not make it out alive.

Kai decided to ignore the dive computer’s decompression instructions and just swam toward the surface. But disaster struck again — his underwater scooter malfunctioned. What should’ve taken 15 minutes to swim now would take nearly an hour.

Elsewhere in the cave, Patrick and Vesa were both still fighting to survive. Patrick was overjoyed when he saw Vesa’s flashlight, a sign that one of his friends was still alive.

For them, it felt like a miracle. Around 9:00 PM, Patrick finally surfaced and rested in the dry part of the cave. Vesa followed shortly after. However, both were suffering from decompression sickness — dizzy and in pain.

Meanwhile, Kai was still swimming manually back to Plura Lake. Miraculously, he eventually saw the block of ice above the lake — but he couldn’t find the hole they had made earlier. He started panicking again, unsure if he could survive in the water much longer.

Luckily, he found the hole. Using his last bit of strength, he broke through the frozen lake and climbed out. He didn’t even care about the cold or wait to recover from the decompression effects. Instead, he ran straight to the trailer van and drove away, thinking he was the only survivor.

What Kai didn’t know was that Patrick and Vesa had already returned to their farmhouse. The two had contacted authorities and believed Kai had also died. But around 2:00 AM, they were overwhelmed with joy when they saw Kai’s vehicle approaching.

By morning, news of the Plura Grotta cave tragedy involving the five Finnish divers spread like wildfire. While recovering in the hospital, the three survivors were questioned by police. They revealed that their two friends, Huttunen and Yari U, had died and their bodies remained deep within the cave.

Authorities hired two expert British divers to attempt a recovery mission, but the risk was too high. The local government decided to leave the bodies and permanently seal off the Plura and Steinugleflåget caves, banning all future underwater diving there.

However, the three survivors could not find peace. They promised the families they would recover their friends’ bodies. But it wasn’t that simple — Kai backed out due to anxiety and panic attacks, and Vesa had not yet recovered from spinal injuries caused by decompression sickness.

Patrick decided to form a new team for the mission. After months of planning, training, and studying the cave’s layout, they successfully recovered the bodies and gave them a proper, honorable burial.

Though the tragic story of the five Finnish cave divers ended in grief, it serves as a powerful reminder of the dangers involved in exploring deep, silent underground caves.