Hello everyone, and welcome back to Scary Interesting. In this video, we're gonna go over three stories featuring caves that are incredibly unique compared to the others covered on the channel. And because of these unique features, they probably never should have been entered at all, as the people in the stories found out.
As always, viewer discretion is advised. [intro music] About 12 million years ago, an underwater volcano formed in the Atlantic Ocean that produced many eruptions over the course of 9 million years. And with the help of tectonic plate movement, the island of Tenerife, as we know it today, was created.
Tenerife is the largest of the Canary Islands and sits about 300 miles, or 480 kilometers, off the western coast of Africa. The Canaries are a chain of islands that are Spanish territory, and Tenerife is the most populated among them, with nearly 1 million people calling it home today. In terms of annual visitation, however, Tenerife sees five times that as one of Spain's most popular and important vacation destinations.
Most tourists come for the beautiful beaches, but the landscape of the island is incredibly diverse for a landmass of just 785 square miles. Central Tenerife is home to dense pine forests, while closer to the coastline, you'll find steep, rocky terrain, beaches, and of course, caves. Unlike some of the places featured on the channel to this point, tourists don't feel an irresistible draw to the island's caves.
Instead, the complex underground systems on the island are more of a hidden gem reserved for those with an adventurous side. Scientists take great interest in the caves of Tenerife, too. That's because many of the island's caves aren't caves in the traditional sense.
Instead, they're actually lava tubes. When a volcano erupts, lava travels outward through self-made channels. And when particularly thick and slow-moving lava seeps out of the earth, it remains extremely hot in the channels while the area around the lava actually cools.
This causes a hard crust to form on top of even the most active lava streams. As the molten hot liquid rock flows over a long enough time, it creates tunnels that remain behind long after an eruption ceases and the lava recedes. Tenerife just so happens to have a lot of lava tubes, also known as galleries, including Cueva del Viento.
This particular one holds the title of the largest volcanic tunnel in Europe at 11 miles, or 18 kilometers, long. And systems of lava tubes can be found all over the island, and many of them connect to one another. On Saturday, February 10th, 2007, a group of nearly 30 people gathered on the western side of the island for a hike that would take them through one of these lava tubes.
The expedition was planned and organized by the Tenerife Association of Friends of Nature, and normally, the outings attracted small groups, which were usually full of familiar faces. But on February 10th, a larger than average crowd showed up, including a handful of scholarship recipients of the Canary Astrophysics Institute. Together, the group set off and began enjoying the picturesque landscapes of Tenerife's peaks and ravines on a gorgeous day.
At around 2 o'clock, they reached the base of a mountain that they'd need to get to the other side of, and there were only two ways that could happen: either over, or through. Since this was more of a leisurely hike, the latter was the better option as a lava tube connected the two ravines. So in a single file line, everyone began entering the tube and crouching under the low ceiling while shuffling through ankle-deep water.
What none of them realized at the time, however, was that they had chosen the wrong tube. Because while the hike was organized by an official nature club, there were no experienced guides leading the group. Instead, one of the club's officials received directions and instructions on his phone from someone who knew the path well.
The group was essentially being led into a potentially dangerous lava tube via just a few notes jotted down on a phone. So when the trail led to a gallery opening, they figured that it must be the one they were looking for, so they continued inside. Had they walked just a little further, they would have found the correct tube nearby, but since none of the tubes had any signs outside, It was impossible for them to know that with the information they had available at the time.
The group advanced further and further inside the lava tube, and by 3 o'clock, they were a little over a mile beneath the mountain when everyone began feeling a little strange. Before anyone could put their finger on exactly what that was, one of them fainted and fell to the cave floor. Then another hiker fainted, and another, until 16 of 29 lost consciousness.
The other 13 closer to the back of the pack were feeling the same effects of whatever caused the others to pass out, but they managed to turn around to escape the tube. Sometime later, at around 4:45 pm, a call was placed to emergency services by those who made it out, and members of several rescue services rushed to the scene. Still inside by that point were 16 hikers who lost consciousness, but before rescuers entered the tube, an important briefing took place between them and those who made it out.
All of them reported the smell of some kind of gas around the time the others lost consciousness, so rescuers would have to be careful not to end up in a similar state as those trapped inside. Beyond that though, the effort to get all 16 to safety was not gonna be an easy one. The tube the group mistakenly entered was at its largest about 6 feet wide and 6 feet high, or 2 by 2 meters, but most of it was even tighter than that.
Thankfully, as rescuers made their way inside, some of those 16 who passed out regained consciousness and were able to make it out of the cave under their own power. As they continued on, somewhere around 5,000 feet, or 1,400 meters, Rescuers found the first of those who hadn't woken back up yet and began the process of removing them. Then, just beyond that, they began to notice the smell of gas that had been reported by those who escaped before passing out.
Throughout the night and into the morning hours of February 11th, rescue workers needed to proceed with an extreme amount of caution. As they located and extracted hikers further and further in, the consequences of being in the tube for long periods of time became known. Eight of the ones that were rescued that were unconscious were airlifted to a hospital with issues that varied in severity.
Most of them had acute breathing issues, but two are in more serious condition, showing signs of muscular injuries from the awkward position they passed out in. As the afternoon of February 11th approached, only six of the original 29 hikers remained inside, but rescuers were concerned about their conditions. The six hikers had been leading the group, and so they were the furthest inside the cave.
And as rescuers advanced toward them, the smell of gas inside became stronger and stronger, suggesting that higher concentrations of it were lingering the deeper you went into the tube. Finally, about 20 hours after the hikers began what they hoped would be a fun, leisurely exploration, the rescue effort took a tragic turn as the last six were discovered dead. All of them had died from oxygen deprivation.
The amount of time that the brain can go without sufficient oxygen is so scarce that they were likely dead long before the first part of the group escaped. It takes just one minute of oxygen starvation for the brain cells to begin dying, and four minutes later, death is just about inevitable. In the aftermath of the disaster, those who were intimately familiar with the lava tubes in the area, said the hikers were in just about the worst place they possibly could have been.
Tenerife is an active volcano island, and just because it hasn't erupted since the start of the 20th century, doesn't mean that there isn't a lot going on underground. As rock melts under the indescribable heat inside a volcano, it produces gases that travel through the network of lava tubes. Volcanic gas is denser than air, so as it builds up and becomes more concentrated, it replaces the breathable air.
Just as those who survive reported, by the time you realize you're in a dangerous area that might not have enough oxygen, it's almost too late. Fatigue sets in and rapidly advances, and once you notice it, you only have moments to reverse it by getting out of the affected area. Three days of mourning was declared by local governments after these six dead hikers were discovered and extracted from the cave.
It was getting late in the evening on August 15th, 1992, as friends Dave, Scott, and Alex dressed in scuba gear and descended beneath the waters of Nickajack Lake in Tennessee. And there was a good reason why they were diving under the cover of darkness. Their plan was to enter Nickajack Cave, which was forbidden by the Tennessee Valley Authority, or TVA, due to the cave being home to an endangered species of bat.
Outside the cave, a heavy chain-link fence protected the entrance, but that didn't stop Dave and his friends. Underwater, there was a gap between the fence and the bottom of the lake, so all they had to do was swim under it. This would actually be their third time in the cave as well, with their second coming only the night before.
And funny enough, the reason for their dive was fish. Dave and his friends were after catfish, and those inside the cave were said to be of mythical proportions— maybe even as much as 200 pounds, or 91 kilograms. During the dive the night before, Dave spotted one of the monsters and got a shot off from his spear gun, but only managed to graze the fish.
Throughout the day on August 15th, he just couldn't get it off his mind. The fish was too big to just let it go, so this night was all about redemption. Now, in a strange way, the cave was kind of a place of second chances.
Just prior to the completion of a hydroelectric dam operated by the TVA in 1967, the cave was actually dry. And one day that year, a man dressed in all black made his way inside and sat down. At the time, he viewed himself as a hopeless addict whose marriage was crumbling as a result of his habits.
Inside the cave, he planned to "end things", but before he went through with it, he sat deep in thought for a few hours. As he did, he had a spiritual experience that completely and instantly changed his outlook. He had come all this way to end it all, but he suddenly saw his place in life in the world.
So instead of the cave being a setting for the end, it was a new beginning, for, if you can believe it, none other than Johnny Cash. As incredible as that is though, the cave has a much deeper history that goes back to the Chickamauga tribe, which used it as a base of sorts for war dances and to scheme out ways to fight off settlers. Then, during the Civil War, the cave was a vital resource for the Confederacy as its high concentration of saltpeter was crucial for the production of gunpowder.
Over the years that followed, there were failed attempts to commercialize it with the main attraction being a stalagmite believed to be the largest in the world. Finally, with the completion of the dam and the Indiana bat being named a protected species in the same year, the flooding of the cave marked the end of legal exploration. As Dave, Scott, and Alex made their way deeper into the cave with their spearguns ready, disappointment began to grow as none of them spotted the fish.
Visibility inside the cave was a bit better in the lake, but not by much, so as much of a letdown as it was, it was hardly a surprise. Around 11 o'clock that night, Dave looked at his air gauge and knew it was time to head out. He looked at his friends and pointed upwards, and after receiving the "okay" hand signal back, the three started their ascent.
As they came closer and closer to the surface however, all they could see with their flashlights was an underwater ceiling which had to have been slightly alarming. Having gone further into the cave than they realized, they were still a bit of a swim from the entrance. After feeling around the ceiling for a while, they descended again to regroup as they swam toward where they believed the way out was.
This is a good time to point out that none of the men were trained or certified in cave diving. While they were experienced open-water divers, cave diving requires a specialized set of skills, knowledge, and equipment. When they entered the cave that night, they had committed one of cave diving's greatest sins, which is that they went in without a guide rope.
Caves that are legal to dive in will often have permanent guide ropes fixed to the entrance that lead throughout the system. In legal caves without permanent guide ropes, and even in those with fixed lines, divers will tie off their own rope to the entrance with the other end attached to a spool on their belt. And it's impossible to overstate just how important this piece of equipment is.
A diver can suddenly panic or become disoriented, or visibility can be reduced to zero. But with a guide rope, divers will always be able to find safety. Without one, divers can easily be doomed in that type of a scenario.
When they tried to surface once again and found only rock above them, their composure evaporated. All three of them then panicked, and in their flailing to find an exit, their fins kicked up all the loose silt that had settled on the rock wall, ceiling, and floor. This then completely blinded the three men, making their situation infinitely worse.
The three men then lost track of each other, and Dave swam one way, while Scott and Alex went to another. Miraculously, moments later, Scott and Alex found the tunnel that leads the entry and surfaced with one of them. As they did, they saw that their air tanks were literally a few breaths away from empty.
But even more alarmingly, immediately, they noticed Dave wasn't with them. After waiting a few more moments with no sign of Dave, Scott and Alex made their way for the exit to call for help. Around 2 am, the 911 call came in to TVA, and rescue agencies started to arrive, but not a single one of the more than a hundred people who respond to the call, was cave diving-certified.
If they wanted certified cave divers capable of rescuing Dave, the closest ones were located at least two hours away. According to the rescue commander of the lead agency, however, getting cave divers to the cave wouldn't be necessary. Based on what was known of the cave system and Dave's inexperience in such environments, this mission was a rescue in name only.
The commander believed that Dave was already dead, either from drowning or hypothermia, and this influenced his decision-making. As the sun started to rise, TVA made a call to Buddy Lane, who was the captain of the local cave and cliff rescue team. During a conference call, Buddy pulled out a map of the cave that was made in 1962, before the dam was opened and the cave was allowed to flood.
On it, he marked where Dave likely was when he split from his two friends, and noticed that there was a very real chance that there were air pockets nearby. If there were, they probably weren't very big, but they could at least sustain Dave long enough to be rescued. So when Buddy learned that the mission was being treated as a recovery, he could hardly believe what he was hearing.
No team anywhere at the time had more rescue experience in the area than Buddy's, and he knew that you don't give up a rescue until a body is found, or enough time passes that the situation becomes unsurvivable. The rescue lead, however, was firm that this was a water rescue and not a cave rescue, so Buddy's pleads to summon the help of certified cave divers, fell on deaf ears. Buddy even offered to come to the scene himself to help organize the rescue effort, but this was rejected, too.
By this point, divers on the scene had already gone into the cave three times only to get turned back, further convincing the rescue lead that Dave would be dead by then. Despite this, Buddy continued to essentially beg to be allowed at the scene, but his offers were repeatedly turned down. So next, with only one option available to him, he called Mark Caldwell.
Mark was an executive with the Federal Emergency Management Agency, or FEMA, and just about the only person with the authority to change the scope of the operation. After hearing Buddy's assessment, Mark rushed to the cave and took the scene over. The first thing he did after assuming command was to bring Buddy and his team lieutenant, Dennis, in to attempt the rescue.
During his call with Buddy, Mark discussed the possibility of opening the dam to reduce the water level inside the cave. But this move would come at a heavy financial cost for the TVA. Upwards of hundreds of thousands of dollars' worth of electricity production could be wasted.
But after mulling it over, Mark ordered that the system operators begin to lower the level in the lake. What Buddy and Mark hoped this would do was open up the tunnel so that more air could reach Dave if he was still alive in an air pocket. Buddy estimated that if this was the case, Dave would only have a few inches of space between the water and the ceiling, and that small of a supply of air would run out soon if nothing was done to get more oxygen to him.
So with Mark's call, the TVA moved more than 3. 9 billion gallons of water out of the lake to drop the level by 14 inches, or 36 centimeters, which was the furthest they could go without disrupting boat navigation on the lake. Once this was complete, Buddy and Dennis hurried inside the cave with their caving gear and some fins they borrowed.
Now, to be clear, Buddy and Dennis were cave rescuers, but not cave diving rescuers. Thankfully though, the reduction in the water level allowed them to navigate without the need for air tanks and full diving gear. After the water was lowered, there was just enough space for them to breathe, and by "just enough", we're talking about as little as an inch and a half, or 4 centimeters, in some places.
Deep inside the cave, Buddy and Dennis called out for Dave and then waited silently to listen for a response, but there was no reply. Pretty quickly, hope of finding him alive started to wane. A little further in, Buddy called out again and waited.
Suddenly, a distant voice came echoing through the tunnel. Buddy and Dennis then looked at each other and hurried in that direction. Inside a small air pocket, there was Dave, exhausted but alive.
He would end up asking Buddy and Dennis if they were angels, to which Dennis replied that they had been called a lot of things before, but angels was never one of them. As they led Dave toward the cave exit, it brought an end to a harrowing 18-hour ordeal for him. During his time inside the air pocket, Dave was convinced that he was going to die.
This tiny space was only 8 inches, or 20 centimeters, from the water's surface to the ceiling, leaving him with a very limited air supply, just as Buddy and Mark predicted. For all that time, he clung to a small stalactite to remain above water, which did conserve his energy, but only moments before the lake was lowered, Dave could feel his breathing become more labored. After so many hours, he had used up all the oxygen in the pocket, which would have resulted in his death if not for Mark's decision and timing.
And although the lake itself was lowered by 14 inches, the water level in Dave's air pocket dropped by only about an inch and a half. Thankfully, this was just enough to open it up to the rest of the tunnel. Dave would also say that it sounded like a train barreling through the cave when fresh, cool air rushed in and basically brought him back to life.
Apparently, during the end of his ordeal, Dave saw visions of two angels that had come to take him to heaven, and that was the reason for his odd question to Buddy and Dennis when they found him. As it turned out, Johnny Cash wasn't the only person to have a life-changing spiritual experience inside the cave. The ordeal Dave endured deepened his faith and gave him his own second chance at life.
Every year, visitors flock to Weeki Wachee wildlife management area just north of Tampa, Florida, to catch a show you can't really find anywhere else. Inside the state park is Weeki Wachee Springs, which is home to a live mermaid show. And tourists come to watch in awe inside an aquarium-like area as divers dressed as mermaids entertain them with synchronized swimming routines.
Interestingly, most who attend the show may never know it, but beneath the underwater stage is a cave system so extensive and dangerous that it's often called "The Mount Everest of cave diving". And in fact, it was mostly unexplored all the way until 2007. Drughts that year finally presented a prime opportunity for cave divers from the Karst Underwater Research Team.
This group would then manage to explore the system and document around 6,700 feet, or 2,000 meters, of passageways. This discovery of tunnels that stretch well beyond 400 feet, or 122 meters in depth, also put Weeki Wachee Springs at the top of the list of the deepest known freshwater cave systems in the US. With this new title, cave divers from all over the world were eager to explore the hidden reaches below the mermaid show.
Unfortunately, the spring isn't exactly the type of cave where you can just show up and dive. First of all, it requires a reservation, but more importantly, conditions have to be just right in order to safely navigate the extremely tight tunnels, because it has a current running through it that most divers find difficult to dive in. This is because, more than 117 million gallons of water flow from the caverns every single day.
And in addition to that already being an insane volume, supposedly, it's one of those things you have to experience to fully understand. In fact, it's been described as trying to climb a rock face with a fire hose blasting down at you. And these conditions have claimed lives inside the system before.
As a result, the only time to explore the system in the safest way possible, is during drought conditions. Florida is a state that gets a lot of rain, and in Central Florida, where Weeki Wachee is located, the area can experience somewhere between 0 and 11 weeks of drought per year, making opportunities to dive the system extremely limited. One of the members of the Karst Underwater Research Team, Marson, was a successful information technology staff member at a local blood center in Gainesville, Florida.
And while he loved computers, cave diving was his true passion. In fact, he was known as a bit of a thrill-seeker by his family and friends, always willing to try new things that would get their adrenaline flowing. Any time he brought up cave diving around his mother, her demeanor would understandably always be sour.
She absolutely hated that Marson had picked up such a dangerous hobby, but he would always tell her that if he ever died while cave diving, then he would die doing the thing he loved most. And also unsurprisingly, although he was trained, certified, and experienced, and by all accounts a careful and cautious diver, this did very little to ease her concerns. Because of where he lived, Marson explored underwater cave systems around Gainesville at least two or three times a week, and by 2010, he had extended his passion into something that could truly help others.
He had taken to rescue diving, like for example, when a diver went missing that year at Vortex Springs in the Florida Panhandle, Marson was one of the volunteers who searched for him, although unfortunately, the diver's body was never located. Two years later, on March 31st, 2012, Marson traveled to Weeki Wachee Springs with the Karst team for another research dive. After the final mermaid show of the day wrapped up, Marson and five other members of the research team suited up and entered the water around 3:30 that afternoon.
The divers then passed by turtles, fish, and manmade rocks to use in the mermaid show on their way to the entrance. Now, unlike many of the caves featured on the channel, the way into Weeki Wachee Springs Cave isn't some wide, grand opening. Instead, it's only about the size of a door, and this tight space constricts the already fast-moving current to 1,800 gallons per second.
After passing through the entrance, the divers begin to encounter some of the tightest sections of the cave at around 100 feet, or 33 meters, on the way to their target depth of 178 feet, or 54 meters. They then reached a large open room, and after a bit of exploring, Marson signaled to the others that he was gonna head for the exit. The others gave him the "okay" hand signal, and he began his ascent as the others followed in behind.
Now, the way up and out is the most difficult part of diving Weeki Wachee Springs because of the current. On the way in, you're following the current, but on the way out, you're going against it. Kind of like flying an airplane through a strong headwind— the process is slow and requires a lot of energy to battle the water.
From around 178 feet, an orange guide rope leads up to the entrance and first takes divers through a large gallery room up to about 142 feet, or 43 meters. At this point, there's a tight crevice section that begins. By following the rope, divers can find their way through the widest portion of it on the way to the entrance.
It's still very tight in this section following the rope, but every inch of space can make a world of difference in this area. These extremely narrow restrictions continue for another 80 feet after that to about the 68-foot mark where things open back up and daylight above can be seen. As they ascended toward the crevice, the five divers behind Marson, watched as he alarmingly and all of a sudden deviated from the orange rope, and instead headed into one of the most constricted portions of the system.
This was a confusing decision to the others, especially since Marson had been in the cave many times before and knew the way out. And not only was he going the wrong way, but it appeared as though he had overcompensated for the current as he rapidly ascended into the crack and then just disappeared. The others continued behind him at a safer pace, but when they finally reached the 100-foot mark, there was Marson, completely wedged in a restriction.
He seemed to be alert as he struggled to free himself from the space, but the opening he had chosen was so enclosed that even divers with side-mounted tanks would barely be able to get through. When cave divers know they'll encounter such tight sections, they'll often wear their air tanks on their sides instead of their backs. This reduces their overall profile and makes it easier to get through tight squeezes.
Marson, however, was diving with a traditional setup, wearing his tanks on his back. This means he had to force himself through, probably very forcefully, only to come to a stop when there was literally no more room to move. As soon as the divers with him saw him, they sprang into action, trying to pull and push him free, but it was no use.
They tried signaling to Marson to establish some communication, but strangely, he acted as if they weren't there. So, with him wedged in this extremely tight space and quickly running out of gas, the others realized they'd need to get help immediately. They then returned to the surface quickly to alert the support team there, and within moments, they were in the water and descending to the crevice.
No more than three minutes later, they reached Marson, and the sight of him was absolutely horrifying. He was still firmly squeezed in the rock walls, and he was completely lifeless with his mask over his forehead and his regulator floating in the current. For the better part of an hour, the divers worked to free Marson and had to resort to literally cutting his equipment off to wiggle him out.
At around 4:45 pm, he finally broke the surface. A quick check of his air gauge revealed that he still had half of his supply left in both tanks, which means he didn't run out of air while wedged in the crevice. Instead, he'd succumbed to something else, and one of the most dangerous conditions a diver can experience.
An autopsy was then performed, and while it was initially speculated that Marson drowned and that his regular came free of his mouth as a result of panic, his cause of death was determined to actually be an arterial gas embolism. As you're probably well-aware, as divers descend, the pressure on their bodies increases. And this pressure does strange things to the gases in our bodies.
Nitrogen is absorbed into the soft tissues on the way down, but on the way back up, it releases back into the blood vessels. And if a diver ascends too quickly, nitrogen causes bubbles in the blood which causes a whole bunch of issues. An arterial gas embolism, however, forms as a result of defying one of diving's golden rules— never hold your breath on ascent.
During this stage of the dive, the water pressure on the body gradually decreases which causes air in the lungs to expand. If a diver holds their breath as this occurs, the gas can expand to the point of bursting the lungs and cause gas bubbles to release into the arteries. And gas bubbles in the arteries are much less forgiving than those formed in the veins.
Just two to three milliliters of air released into the bloodstream that goes to the brain, can cause death, and all it takes for the same thing to occur in the heart is about half a milliliter. This is because, the embolism simply blocks the vessel entirely, leading to a complete loss of blood flow. For this reason, an embolism is fatal more often than not, even in divers who make it safely to the surface.
According to Marson's autopsy, he suffered an embolism during the ascent that caused him to become disoriented, which is why he took the wrong route up through the crevice. As he ascended, a large gas bubble began making its way from his lungs, through the arteries to the heart, where it lodged in place and cut off blood flows to his lungs. Sadly, it's estimated that Marson was dead before the support team even had a chance to enter the water that day.
If you made it this far, thanks so much for watching. As I've mentioned on a few occasions, the cave stories are getting harder and harder to come by. So if you know of any from your home country or that you haven't heard on the channel so far, you can let me know using the story suggestion form in the description.
Anyways, thanks again, and hopefully, I will see you in the next one.
