Deadliest Cave Diving Disaster | The Shaft

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Tatiana: A group of eight recreational
divers entered a sinkhole in the

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ground, but only four would return.

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Their lives forever changed.

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Out of the divers that surfaced,
one would experience the pain

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of losing four family members.

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This disaster was so tragic,
it changed cave diving forever.

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This is the story of the Mount
Gambier Cave Diving Disaster.

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I'm Tatiana, and this is Occurrence.

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On May 28, 1973, a group of nine divers
planned a two day dive at Mount Gambier

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at the Shaft Sinkhole in South Australia.

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Within this group were some
experienced open water divers.

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Christine, Stephen, and Glenn were
siblings and were all experienced divers.

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They had all achieved the highest
qualification available for

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diving at the time, and they
were all diving instructors.

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And Christine was the New
South Wales title holder.

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Her father said at the age of
19, she had already been scuba

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diving for about 15 years.

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They were all raised by their father,
who was also an experienced diver,

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and raised them to love diving too.

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A cousin to the siblings, named John,
was on this trip too, and he had about

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four years of experience himself.

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So, this family in general was very
experienced in open water diving, but

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the allure of the shaft sinkhole was
the hole in the ceiling that was an

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entrance to the clear water below.

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The grassy hole is 3 feet wide and
divers had to be lowered in with a

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rope to the lake about 20 feet below.

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It opens to a huge cave about
the size of a football field.

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It's like 360 feet by 164 feet.

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When it's sunny, a bright
beam of light shines down and

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hits a rock pile in the lake.

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The light is used for guidance,
so divers know where they are.

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As divers get disoriented when cave
diving since it's dark and they can

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only use the lights they have on them.

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This would be attractive to
open water divers that are

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used to clear bright water.

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Being able to see the light on sunny and
even cloudy days is extremely helpful

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with orientation and just generally
being able to know where the entrance is.

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As long as you're in the main
cave and not one of the tunnels

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that branch off from either side.

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You'll understand why soon.

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The first day's dive was successful.

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They extended a shot line 150 feet
into the water to the rock pile and

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quickly explored the area around the
rock pile before ending the dive.

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Their shot line was already in
place, so the plan was for them to

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come back the following morning and
do more or less of the same thing.

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Robert, who was the president of the
dive club for the group, had dived at

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the sinkhole a number of times before
and had created most of the dive plan.

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There wasn't a specific system or
boundaries laid out, but he just generally

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expected everyone would stay in the
main chamber to stay within the max

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depth range of 200 feet and explore.

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After all, they only had the main shot
line from the surface to the rock pile.

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There were no other guidelines laid out.

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He never imagined what
would happen the next day.

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When they returned to the cave they
were exploring, at first things

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were going according to plan.

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Only eight of the divers actually
went into the cave that day.

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Joan stayed on the surface and prepared
food and helped the group in other ways.

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But, at the perimeter of the rock
pile, Robert began to feel strange.

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He was feeling lightheaded, and his depth
gauge told him he was 180 feet deep.

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Since he was an experienced diver,
familiar with the symptoms of nitrogen

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narcosis, he realized what was happening.

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It's 1973, and scuba divers at this
time are using regular air cylinders

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filled with only oxygen and nitrogen.

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This type of air supply limits
the max depth a diver can

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reach before narcosis sets in.

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Mixed gases that would have allowed
deeper diving aren't available for

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recreational divers yet and technical
diving science wasn't established.

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So Robert signaled to his group that
he was returning to the top of the

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rock pile and everyone else signaled
they were going to continue exploring.

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Now, nitrogen narcosis can happen after
reaching 130 feet using normal air.

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The deeper you go, without proper
equipment and procedures, the more

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nitrogen is introduced to the bloodstream.

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The effect it has on the person is
similar to extreme intoxication.

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It impairs judgment and motor function.

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At 185 feet, the air starts to
become toxic, which could lead

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to seizures and all kinds of
things that would lead to death.

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Now Robert did what he said, and
he continued circling the rock

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pile for about 8 minutes while
searching for animal bones.

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During this time, Glenn continued
exploring around the rock pile, and Glenn

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had been paying attention to the amount
of air he had left, and knew that he was

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running out of time to be in the water.

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So, he attempted to tap his
sister, Christine, on the arm to

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remind her time was almost up.

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She was following behind a few others
in the group that were breaking away

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to swim down one of the tunnels that
branched off from the main cave.

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Before he could reach her, she
quickly went over the ledge

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that led out of the main room.

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Glenn figured they just wanted
to look around a bit more, but

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would return and come back soon.

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At this point, Robert was headed
to the surface and could see the

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light of Glenn returning from the
direction the others had gone.

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Robert and Glenn surfaced pretty
much together and found that Larry

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had already returned from his dive.

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And less than a minute later, Peter
surfaced with almost no air in his tank.

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The group quickly realized that those
still in the water would also have very

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low air supply, and limited visibility due
to the clouds blocking the sun in the sky.

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Peter had briefly struggled to find
the entrance due to silt being kicked

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up by divers in the tunnel, and the
low light coming from the entrance.

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What they didn't know at the
time was how chaotic things got

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right when they all turned back.

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So Gwen quickly put on a spare
tank and got back in the water.

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He went to a depth of 225 feet,
where the cliff began to drop off.

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And at the edge, he found
Steven's light and camera.

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The visibility at this point was
practically non existent due to the huge

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amount of silt that had been disturbed.

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Now this is a dangerous
environment for divers to be in.

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It's way too deep and
there's no visibility.

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And Glenn quickly realized this, so
he had no choice but to decompress

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and return to the surface.

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By the time he surfaced,
an ambulance had arrived.

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So Peter decided to check out
the cavern for one more look.

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This was the last chance.

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If the divers from their group
were going to have any chance at

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survival, they had to be found now.

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He was hoping to find anyone
in their group to save, but

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unfortunately, he didn't find anyone.

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And at that point, everyone knew they
were no longer looking for survivors.

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They were looking for bodies.

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So what happened that kept half
of the group from surfacing?

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There was a little hope there was
some way someone survived using

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an air pocket or something else.

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So what happened?

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When Christine, two of her brothers,
and her cousin reached the ledge

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that Glenn lost her at, they paused.

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Christine was starting to feel the
first signs of nitrogen narcosis

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and knew she was limited on time.

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But she had been diving
for 15 years at this point.

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She knew how to combat the effects
by staying focused on what she was

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doing and keeping controlled breaths.

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But she had never been
at this step before.

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She was heading towards being 250
feet deep, but had to travel 300 feet

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through the narrow tunnel to get there.

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She wanted to see how deep she
could go and make a new record,

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but she had less than five
minutes of air and didn't know it.

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At some point, she realized she wouldn't
be able to make it to the end of the

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tunnel and back, so she turned around,
but this was not as simple as it sounded.

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There were no guidelines laid, and
with four divers entering that narrow

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tunnel, the amount of silt they kicked
up meant there was zero visibility.

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She couldn't tell up from
down or left from right.

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And when she reached out her
hand and felt rocks, she couldn't

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distinguish a rock from a dead end.

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Christine knew her time was running
out, and it would be a long shot

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to make it back to the surface
with such little visibility.

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So, in a desperate act, she shot up
towards the ceiling to try to get clear of

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the silt, and Gordon did the same thing.

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Their flashlights were sweeping
all over the place, in every

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direction, trying to find the way
out, trying to orient themselves.

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The ceiling is rough with rocks
jutting out and it's uneven.

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It feels just like the jutting
rocks all around the tunnel.

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There wasn't some smooth surface
for them to guide themselves

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along using their hands.

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Christina and Gordon were in
a false dome in the tunnel.

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They could only see their bubbles
collecting on the surface and

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nothing else around them with
the silt being so encompassing.

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The bubbles created an effect on the
ceiling that made them believe they were

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looking at the ceiling of the actual
main cave, trying to get to the entrance.

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The frantic nature of their actions made
everything worse and depleted all their

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remaining air at a ridiculous speed.

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They became hypoxic and sunk
to the floor of the tunnel.

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While that was happening, John
was swimming further down into

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the tunnel at a rapid pace.

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It's believed the nitrogen narcosis
caused him to think he was heading

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back towards the entrance, even
though he was swimming deeper.

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Now Stephen was between where John
was and where Christina and Gordon

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were, so when he went to turn
around, the silt was too thick for

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him to figure out where he was at.

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When he was found, his buoyancy
vest was inflated, which means at

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some point he was thinking clearly
enough to try a last ditch attempt

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to get his body to the surface.

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It may have worked, but he was
caught on the protruding rocks.

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It would take 11 months to retrieve the
bodies because the day after the accident,

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the police underwater recovery squad was
underprepared to dive in those conditions.

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So much so that it was described as
a quote, learn as you go exercise.

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End quote.

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The following day's attempt was the
same, and so they decided to postpone

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until they could receive naval training,
which would take several months.

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In the meantime, the landowners of
the property wanted the bodies out,

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and eventually the police was sent
in to recover Steven, who was closer

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to the surface, in January of 1974
to get Christine, Gordon, and John.

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Due to how dangerous the depth and
silt conditions made the retrieval,

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the team tried multiple times.

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For several days in a row to get Christina
and Gordon that March they were able to

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recover them But the nitrogen narcosis
the recovery team experienced required

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a one month break for them to recover
in April after great effort Improved

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equipment and a lot of planning.

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John's remains were recovered.

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Now, this disaster and recovery
obviously highlighted that

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changes needed to be made.

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And they were.

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New regulations enforcing the
education of divers wanting

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to go cave diving was created.

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They had to understand the difference
between open water diving and cave diving.

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It also included a new training and
three level certification system that

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would place divers appropriately.

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This tragedy paved the way
for better safety regulations.

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But, what do you think about the
Mount Gambier cave diving disaster?

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Leave your thoughts in the comments
and follow for more stories like this.

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All sources can be found at OccurrencePod.

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com.

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Stay safe and I'll see you next time.