In May of 1973, 8 divers were exploring
a sinkhole in Australia known as The Shaft when something
went horrifyingly wrong. This is their story. [music] Today's video is brought to you by Babbel - one of the top language learning apps in the world. When I started this channel, I never anticipated
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on-screen now or in the description below. So the population distribution in the state of
South Australia is really weird. The largest city is the city of Adelaide
with just over a million people, but the next largest city is Mount Gambier
at just 33,000. This makes the second-largest city in the entire state
over 40 times smaller than the next largest. In fact, the population of Adelaide is larger than
all of the rest of the cities in the state combined, which is just kind of weird to think about. And so, although Mount Gambier is technically
the second-largest city in the state, it's really just a small city. Despite its size though, the city is considered
to be the most important settlement in the so-called Limestone Coast region. It sits right on the border of South Australia
and Victoria, just a few kilometers north of the Southern Coast. It also happens to have been built
on the slopes of a literal volcano, which is also named Mount Gambier. Both the city and the surrounding area are famous
for some of these volcanic features, like the limestone topography, crystal blue lakes,
caves, and sinkholes. On the outskirts of the city are
a bunch of farm fields, and these extend all the way to the
shores to the south. One of these is just a small five-acre area (2 ha)
between Mount Gambier and the ocean, owned by some dairy farmers, and known as
Thompson's Paddock. In 1938, a farmer was on the field at Thompson's Paddock
on a piece of equipment, being pulled by his horses, when all of a sudden, one of his horses tripped
and stumbled over something in the grass. The farmer thought that was weird,
so he stopped his horses, got off the piece of equipment, and walked over
to where the horse tripped. What he found was a hole in the ground about
a foot across that he hadn't ever noticed before. He got down on his hands and knees
to take a look into the hole, and to his surprise, the hole extended for
what looked to be at least 20 feet (6.1 m) down, and then at the bottom,
he could see water. This on its own is kind of amazing and creepy,
but this was only just the beginning. It's not clear how long the farmer had had this field or why he hadn't noticed the hole
in the ground before, and no one is really sure if the horse had
caused the ground to collapse, or if the hole had always been there
and the farmer just hadn't noticed. Either way, that leads to the next question: If the horse had caused the hole to open up, doesn't that mean that it could collapse even further, and that the area around the hole
was now at risk of collapsing? To make matters worse,
he could see from the surface that the narrow opening extended for maybe two
or three feet, but after that, the sides weren't visible. It looked like it widened out, sort of like
an upside-down funnel. In a worst-case scenario, imagine someone
had been walking in the field and accidentally stepped into the opening. They would've fallen 20 feet to the water below, and then because of the shape of the upper section,
they would've had no way to climb back out. All they'd been able to do is tread water
and scream helplessly. This was obviously kind of alarming
for their farmer as well, because following the discovery of this opening,
he decided to try to fill the pit with rocks. So over the next little while, he began to bring
soccer ball-sized stones to the opening and just started dropping them into the water
down below. One by one, the rocks would make a big splash,
and then disappear into the dark water, never to be seen again. They reached the first dozen rocks
and they just kept disappearing. Then, they dumped several dozen into the water. The dozens turned into a hundred, then hundreds, and there were still no trace of the rocks down below. By the time they eventually gave up, they probably dumped
thousands of rocks into the strange opening, and still, not a single rock could be seen
down in the water. It was like the hole was bottomless. In the end, the farmer would just had to be cautious
of the opening and hope that it didn't collapse any further. As you might imagine, news spread
of this weird occurrence, and soon enough, people were coming
to explore the hole. It was eventually determined to be
a limestone sinkhole where slowly, the water had dissolved
the rocks below, leading to this large opening
just a few feet below the surface. Eventually, this foot-wide hole was widened
to be about three feet or one meter, so that could be more easily explored. Then, in the mid-'60s, a diver was lowered
into the cave opening for the first time. From the surface, he was lowered
23 feet or seven meters before finally touching down on the water's surface, and what he saw was that it was
actually more like a small lake. Right below the entrance, it was narrow,
but by the time you're at the water's surface, the room is already 56 feet or 17 meters wide. In addition to that, on a sunny day around noon,
the sunlight shines directly through the opening and creates a sapphire blue beam of light
that lights up the room and the water. From then on, the cave was given the name, The Shaft,
because of this shaft of light. From the water's surface, the diver began
scuba diving down into the cave, and found that it just continued to widen out
the deeper and deeper you go. In this first exploration, he got down to about
69 feet or 21 meters before ending the dive and deciding to come back up. But the craziest part was that
from where he had stopped, he could see all of the rocks that had been dumped
into the cave years before. All of those hundreds of rocks looked like a little
anthill down at the bottom of this massive room, and they were still at least 50 feet (15.2 m)
from where he had stopped. The cave was later mapped to have one massive
chamber where the rocks were located, and then two incredibly deep descending arms
that extend out in almost opposite directions. The main chamber is 460 feet long (140 m)
and 260 feet (79 m) wide at its widest, and the top of the rock pile is 118 feet
or 36 meters below the surface. Then, from the main chamber,
there's a tunnel that extends northwest to a depth of 260 feet or 80 meters. And then on the opposite side of that,
there's another tunnel that extends all the way to 407 feet
or 124 meters of depth. It's thought that these tunnels could stretch
all the way to the southern shores as part of the intricate freshwater drainage system
flowing through the mountains in the area. There are also several cliffs, overhangs,
and restrictions in each of these corridors that make for some interesting features
on the way down. These features, coupled with the crystal clear water and the sheer size to explore,
make it a caver's dream. Importantly, a really accurate map didn't
get made until all the way in 1984, but already by a decade earlier in 1973,
8,000 dives had already taken place inside The Shaft. During all of those dives, the full depth
of the cave wasn't known, and a full map hadn't been made. For all intents and purposes, it was
considered to be bottomless. The newness of cave-diving and limitations
of the then available equipment meant that cavers just sort of went
to the edge of the charted area and then stared off into the abyss,
wondering how deep the cave went. In May of 1973, a team of nine divers
planned to make what they thought might be a
record dive in The Shaft. On the 26th, they all arrived in Mount Gambier
and set up tents at a campground near the famous
Blue Crater Lake. Their goal was to reach the edge of the
so-called Perimeter at 250 feet (76 m) of depth. This is essentially the edge of where
the light from above filters through. Any deeper and the angle of the ceiling
obscures the light, and from then on, the water is
almost pitch-black. This also happened to be right around
an area known as the drop off. It's a point in the cave where the bottom
is no longer visible from the edge above. That's what gave The Shaft this reputation
for being bottomless, because standing at the ledge, you can't see
anything down below, but it clearly extends much farther. All nine of the divers who planned to make
this attempt were dive instructors, but because this was a fairly
ambitious undertaking, they planned to do a practice dive and set up
some equipment prior to their real attempt. So the following day, on the 27th, they got
to the farmhouse on Thompson's Paddock, signed the guest book, and then drove into the
grassy field where the entrance is located. They parked alongside the opening and then
set up the famous tripod hoist system that many of you will probably be familiar with. This hoist is used to lower the divers
into the water down below, and incredibly, despite having been widened, the hole is still too narrow for divers
to be lowered wearing their equipment - it has to be lowered separately. On the way up as well, a wire ladder is set up
for the divers to climb their way out. Once everyone was in the water, they were amazed to see just how big the room
was already at the surface. Next, they set up something
known as a shot line, which is why they were there to do that day. This was a line from the surface that was weighted
and led directly down to the rock pile. This would make their descent smoother
for the record attempt and give them more time to reach the edge. On the practice day, the deepest they went
was about 200 feet (61 m), which was just around the perimeter of the rock pile
and well within the light of the opening. While they were down there, though,
they could see the famous edge off in the distance, which was their goal. The bottom of the cave extended horizontally,
and then just disappeared. After finishing this practice dive
and getting a feel for the cave, they returned to Mount Gambier to replace
some of the batteries on their lights and refill all of their air cylinders. Then, the next day, on the 28th, they were
back at the opening at noon, suited up, and getting lowered back down. One of the divers, a woman named Joan,
decided not to dive that day, so it would only be eight of them instead of nine. She decided to stay up and help with supplies
and make food for the rest of them. So the divers who would be entering
the cave that day would be Robert, John, Peter, Gordon, Larry, and then three siblings,
Glen, Stephen, and Christine. The others all dive back down to the rock pile
at 130 feet (39.6 m), and then continue toward the tunnel
where the ledge was located. At about 180 feet (55 m), Robert started to
really feel the effects of nitrogen narcosis. This is when the nitrogen from the gas divers breathe
dissolves in the blood and creates a sort of impaired,
almost drunken feeling. This was a bit earlier than he normally felt it,
but it was already significant enough that he knew he needed to head back up
a little bit to dissipate the feeling. Now is maybe a good time to mention it that because diving and cave diving
were so new at the time, the protocols used hadn't really been
established like they are today. There were a lot of amateurs who were participating
in it who really shouldn't have been. Like for example, these divers,
although they were instructors, they only had experience in open water
in perfectly clear, bright water. The second thing is that there was
no requirement to be cave-certified. Anyone could just sort of dive wherever
they wanted with minimal oversight. But the final and most alarming thing
was that the safety protocols were wildly different than what they are today. This group of divers planned to do a dive
to a depth of 250 feet (76 m) on regular air. If you're at all familiar with diving,
you know how insane this is. Today, the maximum depth recommended
to use regular air is just 130 feet. Beyond that, nitrogen narcosis starts to kick in
and can impair your judgment and motor function. At around 185 feet (56.4 m),
the air actually becomes toxic and can cause convulsive seizures
in some instances. If you were to have a seizure at depth, your
mouthpiece just falls out, and then you drown. So taking all that into account, there were
now eight divers in the water on regular air already at 180 feet. Robert signaled to the others that he was
heading back to the rock pile, and they signaled back to him that
they were gonna keep going. He then swam around the rock pile,
circling it and checking the area for animal bones that might have sunk
into the bottom. About eight minutes later, he saw Glen's torch
coming toward him. By then, Robert was close to being out of air, and so
was Glen who had been watching his gauges. The two of them caught up with one another,
and then surfaced at around the same time. Larry surfaced around the same time as well,
and then 30 seconds later, Peter surfaced and he had essentially no air left. He also said that he hadn't seen
any of the other divers. All of a sudden, everyone's stomach dropped
as their realization set in, especially Glen whose brother and sister were
still down in the water next to no air left. A few minutes earlier, the group that had
continued on without Robert, were swimming and taking pictures until
they got to about 200 feet. Glen and the others were swimming along
a ledge along the bottom, and he saw his sister just a few feet away from him. Everything was normal, the light above
was still bright, and about five minutes total had passed
since they started their dive. Around this time, Glen was feeling kind of
groggy from the narcosis, and decided that he'd gone far enough as well. He checked his gauges and saw that
he was getting low on air, and knew that since everyone had the same
amount of air, they'd also be running low. To be on the safe side, he decided to head
back up, but before he did, he wanted to signal his sister, Christine, to let her
know that she should probably head up too. He went to tap her on the shoulder,
but before he did, she started kicking her fins away from him
and then out of reach. Not wanting to spend any more time down there, he figured they'd probably all follow along
not too long after him anyway, so he just started up for the surface. Then, he met up with Robert, and the
two of them surfaced together. Around this time is when all hell
broke loose in the cave, and a combination of factors led to this being perhaps
the deadest cave-diving incident in history. Right before Glen started heading up, Peter was also feeling pretty impaired
by the narcosis, and wanted to check Glen's depth gauge. He swam over to him, but Glen started heading up
before Peter could read it. Peter sat there for a moment, scanning the
clear water at the bottom, and then noticed two other divers
moving towards the exit. He checked how much air he had left, and that's when
he realized that time was up. Then, he turned to where he thought the exit was and realized that the cave had gone
almost completely dark, and he had no idea which way the exit was. That day, shortly after the group entered the cave,
clouds moved into the area and severely limited the amount of light
shining through the opening. Peter started swimming around,
searching for the exit, but in just a few short moments, the area
had become heavily silted, and the divers were scattered all over the place. Three of these divers had been grouped together
near the deepest section any of them had explored. In order, Christine was in front, Gordon was next,
and then Larry was in behind. Larry and Gordon checked their gauges
and realized they were dangerously low on air. They signaled it was time to head up,
and then in a panic, started swimming almost directly upward
rather than diagonally with the ceiling. In these limestone caves, sometimes,
pieces of rock cleave off and create dome-shaped depressions in the ceiling. It's thought that the expelled gases from the divers
had collected in one of these pockets and created a mirror-like effect on the ceiling, similar to what the surface near the entrance
would've looked like. In their impaired state, their flashlights
bounced off this mirror, and in their panic, they thought they were
swimming in the right direction. Then, they would've swam directly up
and hit the ceiling right above them. Gordon and Christine started frantically
waving their flashlights around, terrified, looking for the exit. Right then, Larry's light went out. He dropped away from the ceiling for a moment
and miraculously, it turned back on, and because he had drifted down, he managed
to see another diver off in the distance. He swam toward the diver and then
the angle was just enough for him to see the real entrance far ahead. He bolted for the entrance and surfaced right around
the time Glen and Robert did. Peter had also managed to find his way out of the silt
and surfaced right after Larry. Upon seeing that four people were still missing,
including his brother and sister, Glen immediately grabbed a spare tank
and dove back down to try to find them. He got to the edge of the cliff at 225 feet (68.5 m) and found his brother's flashlight and camera
resting on the bottom. He also found that any further in was completely
silted out - visibility was basically zero. But desperately wanting to find his siblings, he went over the drop off and into the silt. As soon as he entered the cloud, he couldn't even see
the hand in front of his face, and he started to panic. He immediately swam back out and then
to the edge of the rock pile, and then he just stared into the abyss for some time, hoping to see any sign of them. Eventually, he was forced to return to the surface. Peter went down following Glen's return,
but he also found nothing. By then, an ambulance had arrived and everyone knew
there was no hope of finding anyone alive. Shortly after that, police arrived and planned
for a body recovery the following day. The next day, police divers went down
into The Shaft and got to 200 feet, but found that the cave was still very stilted out. They were already at the limit of their capabilities, and weren't able to locate any
of the bodies that day, or the day after during a second search. Following the second search,
police called it off entirely until they could get additional training
from the Navy, because the depth of the recovery
was groundbreaking, and pushing the edge of the training they had. This would take at least several months to get
their recovery squad up to speed. In January of the following year, before the
bodies had been recovered, the landowners let a film crew who were
making a cave-diving documentary, enter the cave to do some filming. The crew had already filmed several of
the others in the area, and wanted to include The Shaft as well. On the 22nd, they got down to about 50 feet of depth,
and using professional lighting equipment, they lit up the cave so bright that it was
like daylight inside. While they were getting set up, a technician
was looking at two of his teammates, when he noticed what it looked like a
third person behind them. Kind of freaked out, they went over
to inspect the area and realized that it was a body in a wetsuit. They immediately stopped all filming and surfaced, and called the police to let them know
someone had been found. The next day, police retrieved the body,
which was stuck under a narrow ledge just 50 feet deep into the water. They went down to 180 feet that same day
and still weren't able to find any of the others. The one they did recover was later determined
to be Stephen - one of the siblings. By March of that year, the landowners
had become increasingly uncomfortable that there were still three people somewhere
down in the cave, so they sought the help of some more experienced
divers with better equipment. On March 9th of 1974, this team of divers
went down and began a search of their own, and would find a person lying on their back
at 185 feet on the bottom. They also found another person directly
underneath them. Then, 20 feet deeper, they found the final individual - the body of John beneath a rock ledge. His body wasn't able to be recovered
until a month later in April because of the depth and the way
the body was wedged. Almost a year earlier, on that fateful day, it's thought that Christine and Gordon
had run out of air while in the dome-shaped pocket on the ceiling. It's been suggested that they died
holding one another, knowing they were out of air and
there was nothing they could do. This is why they were recovered so closely together. It's not clear exactly who saw John, but
one of the survivors mentioned seeing another diver swimming strongly and
deeper into the cave while everyone else was returning to the surface. This is thought to have been John
who was found the deepest in. It's thought that he was severely
affected by nitrogen narcosis, and that's why he was going
in the opposite direction. Finally, not much is known about
Stephen's final moments. He was obviously found much higher
than the rest of them along the ceiling instead of the bottom. When he was found, his buoyancy device was inflated, which kept him buoyant and stuck to the roof. It's possible that in the silt or in the dark,
he tried to find the exit by floating to the ceiling and then crawling along it. He might have then run out of air
before making it out. However, since no one saw him, we'll never
really know his final moments. This accident, as far as I can tell,
is the worst in cave-diving history. And in the few years preceding this incident,
there were several other fatal incidents in nearby sinkholes in the Mount Gambier area. The Shaft disaster was the final straw and led to the establishment of the
Cave Divers Association of Australia, with the goal of regulating the industry to prevent
further tragedies from occurring. With the benefit of hindsight, we know that these
divers should not have entered the cave without specific knowledge of cave-diving. It's also easy to criticize their use of air
instead of a mix, but back then, specialized gas mixtures
just weren't widely available. They also should have used guide lines
to explore those uncharted sections to avoid getting lost when the cave silted out
or when it became dark. And in fact, these divers knew that
lines should be used, but decided not to use them because
of the size of the group they had. They knew that the lines would likely get tangled,
which would've been even more dangerous. In reality, for a dive like they did, they should
have simply had a smaller group where lines could have been used. Thankfully, following the establishment of the
CDAA and other similar organizations, the rate of cave-dive deaths has been
drastically reduced ever since. Hello everyone. My name is Sean,
and welcome to Scary Interesting. Thank you all so much for watching, and hopefully,
I will see you in the next one.
