- [Narrator] Caving or spelunking is not an activity for the fainthearted. A term used for exploring
the extremes of cave systems. The deeper you go, the less light, space and
even breathable air there is. Sounds like my worst nightmare. But imagine squeezing
yourself over jagged rocks and through impossibly tight
spaces in the pitch black, when all of a sudden, you come across a cave
lined with crystals, lots of crystals, sparkling structures stretching
from the cave's floor to its ceiling, with some as long as a school bus. But as mesmerizing as this place looks, you wouldn't have long to
marvel at its impossible beauty, well, if you wanna make
it out alive, that is. Why? Well, get your hard hat
and your walking boots on as we cover what makes
this giant crystal cave one of the most deadly natural
phenomenon in the world, and look at some other caverns
that despite their splendor, you should never step foot in. (upbeat music) A crystal clearing. Whether it's their supposed healing powers or the way they sparkle in the light, we humans have been obsessed with crystals for as long as we can remember. So back in 1910, when miners from Naica, Mexico discovered a cavern with
short sparkly minerals lining the walls, you can imagine their excitement. They'd found the Cave of Swords, a crystal filled cavern some
390 feet below the ground. Now, miners didn't know this at the time, but Naica lies above an
underground magma chamber some two or three miles
below the Cave of Swords. Over the course of some 500,000 years, the magma heated groundwater
and oxygenated surface water gradually began to change
the minerals in the area. Then, as the temperature of the cave started to drop below
133 degrees Fahrenheit, gypsum crystals slowly began to form. In the Cave of Swords, this temperature transition
happened relatively rapidly, and today it sits at around
116 degrees Fahrenheit, meaning the crystals only had a chance to grow a little over
three feet in length. Still, a three foot crystal is a pretty magnificent thing to behold, let alone a whole cavern full of them. The Cave of Swords was the prize
find of Naica for 90 years, until the year 2000, when miners were drilling a new tunnel through the Naica Fault. They delved 600 feet deeper
than the Cave of Swords and suddenly stumbled across an even more jaw dropping chamber. The Cave of Crystals, a very inspired name there, shall we say. It was completely flooded and had to be drained
to get a better look, revealing that the walls and floors were chock full of gigantic gypsum beams. This was unbelievable. Not even a year before, the Pulpi Geode had been
discovered in Spain, boasting similar gypsum crystals that reached some six feet,
seven inches in length, but these were a whopping
37 feet in length, more than five times the
size of those in Pulpi, with the biggest of them
weighing a back-breaking 55 tons, making them the largest
crystals to ever be discovered. But the mass of these structures isn't the only thing stopping you from nabbing
a souvenir or two. The cave of crystals is a
sizzling 136 degrees Fahrenheit, which is the reason why these crystals have
been able to grow so big in comparison to those in
the cooler Cave of Swords. For some context though, that's hotter than the maximum temperature ever recorded on the planet's surface. Okay, but pack some
water and a portable fan and you're good to go, right? Well, not exactly. This cave is a giant sweat box with humidity levels reaching 99%. Because the air is so hot and humid, the coolest place in the cave would be the inside of your lungs. As a result, water would condensate there, effectively drowning
you from the inside out. Without proper protection, people can only endure
10 minutes of exposure in the cave at a time. However, once mining operations
in the area ceased in 2015, the cave was allowed to re-flood, protecting the giant crystals within and closing it off to all
researchers and visitors alike. So unless you like the idea
of scuba diving in a grave, sorry, cave 980 feet underground with almost no natural light, these incredible crystals and the death trap they're found in are off limits for the foreseeable future. You know what's not off limits though? Those like and subscribe
buttons down below, and that way, you'll never miss another one
of my amazing videos again. All done? All right, let's keep exploring. Mount Rainier Ice Caves, woo. Those crystal caves were hot, so wear better to cool off
than Mount Rainier's Ice Caves in Washington, USA? Ice caves like these form
when temperatures rise and melt water runs
through or under a glacier, leaving behind modeled
passageways or caverns within the glacier itself. That's pretty extraordinary, but photographer Matthew Nichols was able to snap something
even more spectacular in one of these seasonal caves. When the sun hits the top of the glacier, its light is refracted, creating this colorful
masterpiece on the cave ceiling. Man, it'd be so tempting to just perch on a rock and
gaze at that rainbow roof for hours on end. But despite the pretty colors, this isn't a place that
you want to dawdle in. No prizes for guessing that
ice caves are really cold. Typically, these frozen caverns are a bitter 15 degrees Fahrenheit. Now, your normal body temperature is around 98.6 degrees Fahrenheit, but if it drops below just 95 degrees, your body enters hypothermia. This is when your heart,
nervous system and other organs stop functioning normally. And left untreated and exposed, you could be dead in a matter of minutes. So staying here too long or failing to wrap yourself
up properly could be fatal. Yet, it turns out that
chilly conditions here are actually the least of your worries. During the warmer months, melting occurs in the
Mount Rainier Ice Caves. And I'm not talking about drops of water, chunks of ice the size of small cars have fallen from the cave's ceiling. Even if you manage to
dodge a bulky block of ice, you may still not get out
of there in one piece. Ice caves like the one at Mount Rainier are prone to collapsing due to the melting in the
warmer southern months. As recently as 2015, collapses in nearby ice caves have claimed several lives
and left many badly injured. Well, you don't have to tell me twice. I'm gonna stick to looking
at rainbows in the sky. Lechuguilla Cave. Back down south in New Mexico, you'll find the entrance to the eighth longest
explored cave in the world, Lechuguilla Cave. At 150 miles long, reaching 1,604 feet deep, it's the second deepest explored
cave in the entire U.S., and it's also considered to be the most beautiful
and well decorated cavern in the world with thousands of rare geological
formations hidden within from giant gypsum chandeliers and 15 feet tall soda straw stalactites to this peculiar bubble formation stained in a perfectly straight line by the slowly decreasing water level over hundreds of thousands of years. Man, what I wouldn't do to see those things with my own eyes. But be warned, you don't wanna spend too long soaking up these stunning sites because the humidity
levels here can hit 100%. In such humid conditions when the air's saturated with water, our sweat can't evaporate, preventing us from cooling down. While trekking through
this super long cavern may sound like a good
way to shed a few pounds, walking in such testing conditions could put you at risk of
exhaustion and dehydration. To make matters worse, Lechuguilla also contains
many ditches and drops, with some vertical pits plummeting down a vertigo
inducing 300 feet. For reference, falling down there would be like jumping off
the Statue of Liberty. Something tells me that
exhaustion in the pitch black and dramatic drops probably
aren't the best mix. It's so dangerous that the historic cave has
been closed to the public, with only the most experienced
explorers and researchers permitted access. And even then, back in 2014, a rescue team was called to retrieve a stricken caver volunteer who'd only descended 180 feet in the cave, barely 10% of its known depth. Yeah, I think I'm good at
the surface level, thanks. Grjotagja. Tucked away off Iceland's Lake
Myvatn lies Grjotagja Cave. It may not look like
much from the outside, but inside, this cavern is home to crystal clear,
bright, beautiful waters. The location is so picturesque that it was even the hookup
place for John Snow and Ygritte in "Game of Thrones." Yet, that ain't the spiciest
thing about this cave. The standout feature of
Grjotagja is its warm waters, which are heated by volcanic
activity deep within the earth. Up until the 1970s, the cozy temperature of Grjotagja's water made it a popular bathing site, with people flocking to the cave for some respite from
the ice cold outdoors. But the good times didn't last long. During the 1970s and '80s, volcanic activity increased, raising the water to a scalding
140 degrees Fahrenheit. At this temperature, just five seconds of
exposure to this water could cause life-threatening
third degree burns. Fortunately, the temperature of the water has since cooled down to a more comfortable
110 degrees Fahrenheit. Still, with the constant
threat of volcanic activity unexpectedly heating the water again, taking a dip here is one
heck of a high stakes gamble. So if you're not looking to
get boiled like a potato, I'd advise you to think twice before stepping foot
in Grjotagja's waters. Abaco Island Caves. The Bahamas is best known for its pristine white sand
beaches and heavenly waters, but it's actually
underground and underwater that the scenery gets
even more picturesque. Beneath the warm pine forests of Abaco Island in the northern Bahamas lie a series of marine caves
extending for over nine miles. And it's in these caves, divers can find the Glass Factory, caverns full of intricate
calcite formations. These stunning crystal roses along with stalactites and stalagmites litter the ceilings and floors, which make the entire place look impossibly beautiful and dangerous. These formations all
developed during the ice ages when the sea level dropped dramatically, leaving the caves dry and
dripping with mineral rich waters. Gradually, these mineral deposits built up into the structures lining the ceilings and floors
of the Glass Factory today. Now flooded, it may look like
these fascinating formations are capable of dealing any
clumsy divers a sharp stab, but it turns out that these
are incredibly delicate. That's not to say there
aren't other dangers lying in this watery wonder, however. Suspended clouds of hydrogen sulfide can be found throughout
the caves at Abaco Island. Not only does hydrogen sulfide emit a smell like rotten eggs, ugh, it's also pretty damn dangerous. While divers breathe compressed
air through dive tanks, hydrogen sulfide can penetrate
through wetsuits and skin, leading to nausea,
delirium and even death. Imagine throwing up in your snorkel, before going into a state of confusion and then finally leaving
this mortal coil, jeez. As spectacular as the underwater caverns of Abaco Island look, I think I'll be sticking
to The Bahamas' beaches. Cueva de Villa Luz. As you make your way down into
Mexico's Cueva de Villa Luz, the first thing you notice are the pools of
beautiful turquoise water. Looks pretty inviting, right? Well, that's until you
learn the terrifying truth about this place. See, that cloudy tinge in the water isn't the work of an overpriced bath bomb. Nope, it's our old foe
again, hydrogen sulfide. But unlike the pockets of it
found in the Abaco Islands, this gas isn't just in the cave's water. It permeates the air too. And as I've said, swimming through hydrogen
sulfide can get ugly, but its presence in the
atmosphere is just as dangerous. All it takes is five hydrogen sulfide
particles per million or PPM to lead to nausea and breathing problems. Yet, the concentration of hydrogen sulfide in Cueva de Villa Luz can reach a dizzying 210 PPM. At these levels, explorers can expect
severe conjunctivitis, irritation to their respiratory tract, as well as pulmonary edemas, which are potentially
fatal buildups of fluid in their lungs. And just in case that
wasn't deadly enough, indigenous Zoque people conduct an annual religious ceremony here, which turns Cueva de Villa Luz into an even bigger death trap. Each year, they throw the ground up paste of the barbasco route, known as rotenone, into the water. Rotenone, which is a toxic compound, kills the fish that live
in the cave's water. But it's not just Nemo who needs to watch out
for this perilous paste as humans too can feel
the effects of this stuff. Ingestion of rotenone can cause
inflammation to the throat, gastric pain, vomiting,
incontinence and even seizures. So unless you wanna be
sleeping with the fishes, I'd give Cueva de Villa Luz a miss. Orda Cave. Underneath Russia's Ural
Mountains lies Orda Cave, a place that looks more
like a swimming pool in a luxury spa resort than a cavern. But this all natural
gem really does exist. The waters of Orda Cave
are kept crystal clear thanks to the gypsum material
that the cave's made out of. Essentially, gypsum attracts
clay particles together to form clumps known as floccules. When these floccules get large enough, they eventually increase in weight and sink to the bottom of the water. As a result, divers in the cave are able to see over 150
feet in front of them. Sounds like these are idyllic
conditions to take a swim in, but that would be too easy, wouldn't it? At Orda cave, the water temperature drops down to a bone-chilling 40 degrees Fahrenheit. Unsurprisingly, the only
way to survive a dip here is by wearing a wetsuit. Without it, just five
minutes in this wintry water will lead to a loss of dexterity. 25 minutes later, you're likely to lose consciousness. Any longer and you'll
face a frozen finish. The waters of Orda Cave aren't only home to freezing
temperatures, however. Some divers have claimed they've seen a maiden in a white gown known as The Lady of the
Cave floating in the waters. Haunting as that image is, she's said to protect and guide divers that enter the perilous cavern. The Lady of the Cave hasn't
saved everyone though. The freezing waters of Orda have apparently claimed the
lives of around 300 divers throughout the years. Gee, who'd have thought trusting a mysterious
floating underwater figure with your life could lead to a bad ending. The Shaft. In 1938, a farmer in South Australia stumbled across a one foot
wide hole in his field, but this wasn't the burrowed
home of a rabbit or badger. It turned out to be the
opening to The Shaft, a giant underground cave
stretching down far, far below. While the way into this
place looked small, the main chamber was anything but. In all, the colossal cavern
stretched down some 460 feet. Oh, and one more thing, it's underwater, so to explore it, anyone brave enough needs a wetsuit. Sinkholes like this
exist all over Australia, with some like the nearby Kilsby Sinkhole big enough to explore scuba style. But as mesmerizing as shots
of these sinkholes look, the shaft is the site of
a truly terrifying tale. Back in May, 1973, eight divers set about
exploring the submerged cavern. Everything was going to plan until the divers left the sunlit chamber and stumbled upon a side tunnel. At this point, they were at depths where the effects of nitrogen
narcosis could be felt, somewhere between 100 and 300 feet. Nitrogen is a major part of
the air we normally breathe, but when divers descend into deeper water, the pressure of the nitrogen leads to more of its particles getting absorbed into the bloodstream, and the higher the nitrogen concentration in the bloodstream, the slower the nervous system becomes. As a result, sufferers of nitrogen narcosis experience intoxicating effects like confusion and disorientation. Luckily, some of the
more experienced divers recognized their nitrogen
narcosis symptoms and returned to the surface. However, four still
remained deep underwater. To make matters worse, they disturbed the silt
sediment in the side tunnel, obscuring their vision completely. Imagine that, not only are you delirious some 100 feet underwater, but you also can't see
anything around you, practically blind. And with the ever-increasing
effects of nitrogen narcosis, the four remaining divers sadly never made it back out of the shaft. Kilsby Sinkhole is no better, having claimed some 12 lives in similar accidents from 1969 onwards. So no matter how enticing
those sinkhole waters may look, stay out of those holes. Nutty Putty. It's easy to get lost in the rolling hills of this picturesque part of Utah. However, peaceful as this place looks, it's actually the sight of one of the world's deadliest caves. This hellhole called Nutty Putty contains some 1,400 feet of chutes and crazily
claustrophobic tunnels. Nope, nope, nope, nope. That's a 100% nope from me. For some reason, hardened cavers relish crawling through those teeny tiny spaces. One such explorer by
the name of John Jones did exactly that in November, 2009. About an hour into the expedition, John attempted to crawl headfirst through a tight passage in the cave, squirming forward with his
hips, stomach and fingers, but suddenly, John
realized he'd gone too far. He was upside down and stuck
with no room to turn around. Oh, and all of this was happening almost 400 feet from the cave's entrance. Completely trapped, John
tried to keep moving forward. He exhaled, allowing his flattened chest to fit slightly further down the tunnel. But when John inhaled again, his chest expanded, and now he was even more firmly wedged. Luckily, John's brother, who was with him, came across his trapped sibling and called rescue teams for help. Workers tried to pull Jones out leg first using a rope and pulley system. Slowly, the rescuers began to draw John out of the tight passage, but then disaster struck. An equipment failure plunged John back into where he'd been trapped, and now he was even more stuck. Despite continuous efforts
by the rescue workers, John soon became unresponsive. After more than 24
hours wedged upside down and wedged between the smallest of gaps, the pressure on John's
body became too much. Sadly, John didn't make it. And even after his passing, the mission to retrieve John's body was deemed too dangerous, so a decision was made to make the cave arresting place for John. Nowadays, Nutty Putty is
completely closed off, and the memoriam dedicated to John Jones serves as a reminder of just
how lethal this cave is. Little Neath River Cave. There's something super peaceful about a gently flowing river, isn't there? Well, most of the time. You see, this here isn't just a river. It's also the entrance to the deceptively dangerous
Little Neath River Cave. The cavern found in south Wales has become a popular exploration spot with experienced cavers. To get through the entrance alone, cavers have to crawl on
their hands and knees on the riverbed before entering the cavern through a gap that's barely wide enough
for a person to fit through. And it's not just the entrance
that's a tight squeeze. Some of the passageways in
this cave are so confined that cavers have to remove their helmets in order to fit through. But getting stuck in
Little Neath River Cave isn't the only thing that
explorers have to watch out for. It's also prone to flooding if there's a sudden surge of rain. Can you imagine the turmoil of struggling to squeeze through the tight gaps of this cavern? Then all of a sudden, you're up to your neck in water. If that wasn't terrifying enough, cavers have to navigate
a 500 foot long passage with a ceiling so low, they must crawl along
on their hands and knees while they're almost
completely submerged in water. Those brave enough to take
on Little Neath River Cave are at least rewarded by the incredible calcite formations that this cave has to offer. Cool as that looks, there's no way you'll see
me crawling along a riverbed to catch a glimpse of it. Colossal Caverns. Located in Abkhazia, Georgia, Krubera Cave is deep, so deep that it's known
as the Everest of caves, with the deepest explored point laying around 7,215 feet below. Okay, that's around a 1/4
the height of Everest, but still it's about the same
as five Empire State Buildings stacked on top of one another. In all, a dissent down this
colossal cave system and back up can take an eye watering two weeks. It is a terrifying, winding,
wet series of passages that seems to never end, with some sections so flooded, that diving equipment has
to be used to move on. Luckily, Krubera isn't
just a straight down drop, but that doesn't mean you couldn't do some damage with a fall. One particular pit
known as The Big Cascade plunges down almost 500 feet. Imagine stumbling across that in the dark. Terrifying as that sounds, some caves possess even deadlier drops, usually caused by erosion from powerful underground waterfalls over thousands of years. Inside Georgia's Ellison
Cave is Fantastic Pit, a shaft dropping straight down
a stomach churning 586 feet. If you took a misstep and
fell down this hellhole, it would effectively be like jumping off
Seattle's Space Needle. It doesn't sound too fantastic to me. If that doesn't give you vertigo, this next place certainly will. The Miao Keng Shaft in Tian Xing, China descends down a skin-crawling 1,660 feet, making it the deepest
unbroken vertical shaft in the entire world. If you were to stumble
down this sizable shaft, you'd be falling for over 10 seconds. You can't deny that these
are all gorgeous caverns to view from the bottom, it's just the getting to the
bottom bit that scares me. Kitum Cave. With lush green vegetation surrounding it and a waterfall streaming
over its entrance, Kitum Cave in Mount Elgon
National Park, Kenya wouldn't look out of place
in a holiday brochure. But picturesque as this scene looks, Kitum Cave holds some sinister secrets that make it one of the
world's deadliest caves. For centuries, elephants
have ventured into the cave to scrape away at the
cavern's salt rich walls. I'm sure meeting an elephant in a cave would be a once in a lifetime experience, but with these burly beasts flattening around 500 humans a year, I wouldn't be too keen on stumbling across one in a dark cavern. But for some, the risk of an elephant end wasn't enough to put them
off visiting this place. In 1980, Charles Monet went
exploring deep into Kitum Cave. While he wasn't struck
down by an angry animal, this cavern had an even nastier
surprise in store for him. After he'd finished exploring, Monet left Kitum Cave and returned home. Soon after his excursion, Monet came down with an
excruciating headache. Fever, nausea and vomiting quickly set in, forcing him to visit Nairobi Hospital. Not long after, his vomit was black and fluids leaked from
every orifice in his body. Sadly, it all became too much and Monet crossed the great divide. Seven years later, a young Danish boy was
admitted to Nairobi Hospital with the exact same symptoms
that Monet had experienced. So what did the two of
them have in common? They both visited Kitum Cave. A research investigation was launched to find what in the cave was
the source of the men's demise. Turns out it was bat poop. Yep, you heard that right. The excrement of Egyptian
fruit bats deep inside the cave was found to contain marburg virus, a virulent disease that causes the gruesome
symptoms seen in the two men. In fact, it's so deadly that the average case
fatality rate is 50%. Man, what are those bats eating? Elephants or no, I think that's enough reason
to give Kitum Cave a hard pass. Which of these incredible
caves scared you the most, and are there any others that you know of that we should probably avoid? Let me know down in the comments below, and thanks for watching.
