South Africa Cave Dive: Recovery Mission

Summary

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Real Survival Stories: South Africa Cave Dive – Recovery Mission

Podcast Host: John Hopkins | Guest: Don Shirley
Date: April 29, 2026

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Episode Overview

In this gripping episode of Real Survival Stories, host John Hopkins explores the perilous world of deep cave diving through the extraordinary ordeal of Don Shirley and his close friend Dave Shaw. Their mission: to recover the body of a diver lost a decade earlier in Bushman's Hole—the planet's third-deepest freshwater cave—in South Africa’s Kalahari Desert. The story delves into their profound friendship, technical expertise, the high-stakes recovery mission, and the tragic consequences that unfold in one of Earth's most hostile environments.

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Key Discussion Points & Insights

1. Bushman’s Hole: The Setting and Its Dangers

• Introduction to the Cave: Bushman’s Hole is described as an immense and deadly sinkhole, a “submerged natural cathedral” reaching unknown depths (00:58).
• Extreme Conditions: The cave is a “dead zone,” with pitch-black waters and life-threatening pressure changes, where “the cave is eating [the light] up. It’s a dark, dark place.” (Don Shirley, 07:01 & 23:25)

2. The Discovery of Dion Dreyer’s Body

• On a record-setting 2004 dive, Dave Shaw stumbles onto the remains of Dion Dreyer, a diver who disappeared ten years earlier (03:02).
• Dave attaches a line to ensure the body can be found again. Dave and Don decide, wordless and almost telepathic, to plan a recovery mission—a choice that will change many lives (05:34).

3. Don and Dave: Kindred Spirits

• Don’s Diving Background: A veteran diver and former army instructor, Don Shirley’s passion began at age 10 following a visit to Wookie Hole in England (10:33).
• Partnership with Dave: Their bond is immediate and deep, “like brothers,” and they often refer to their underwater maneuvers as a ballet, or “Batman and Robin” (Don Shirley, 16:13).
• Dave, though a relative novice, quickly masters advanced dives under Don’s mentorship.

4. Mission Preparation and the Dive Plan

• Logistics: The recovery operation involves meticulous planning, multiple divers, support teams, medics, police, a documentary crew, and even a mobile recompression chamber (18:05–19:10).
• Safety Protocol: Each diver is to prioritize their own survival—“There are to be no heroics.” Both Don and Dave explicitly state they do not wish to be recovered should they die (21:04).
• The Relay System: Dave retrieves the body and passes it to Don at 220m, who then passes it up through a chain of support divers.

5. The Descent: Into Darkness and Crisis

• Initial Descent: Don describes a feeling of serenity and weightlessness juxtaposed with the pitch-black menace of the cave (23:25).
• First Signs of Trouble: Don expects to see Dave’s bubbles during ascent but finds only darkness. Spotting Dave’s unmoving torch deep below, he realizes something’s wrong (25:05–26:02).
• Equipment Failure: Don’s rebreather controller implodes at 250m, a sound he knows well:

  “I’ve heard that thud before.” (Don Shirley, 27:12)

6. Don’s Ordeal: Near-Death and Recovery

• Battling Equipment Malfunction: Don must manually manage his oxygen levels, risking oxygen toxicity or running out of backup gas (27:33–29:08).
• Choosing to Survive: Unable to reach Dave and faced with crisis, Don makes the gut-wrenching decision to ascend:

  “This is where you’d cut the rope. So now I must leave.” (Don Shirley, 30:05)

• Acute Physical Trauma: Extreme vertigo, vomiting, and loss of consciousness plague Don during the ascent. His ingrained training saves him (“I do it completely by remote... Just like you would do when you’re driving a car and you need to stop the car in an accident,” 36:09). He clings automatically to the line, spinning through black and white blurs (37:04–38:21).
• Physical and Mental Challenge: Every movement induces vomiting; he must grip the rope simply to stay oriented (40:00). “I can only stay where I am. And anytime I try and do something, I spin.” (Don Shirley, 40:33)

7. Trauma and Survivor’s Guilt

• Emergence and Rescue: After over 12 hours in the water, Don is extracted, barely conscious, suffering from decompression sickness, and placed in a recompression chamber (43:24).
• Aftermath:

  “I couldn’t walk unless I had someone to lean on. My eyes were crossed, I couldn’t see properly, I couldn’t balance in any which way...” (Don Shirley, 44:05)

• His wife, Andre, rushes to his side, beginning the journey of recovery (44:26).

8. What Happened to Dave Shaw?

• Accident Analysis: Video footage from Dave’s helmet camera shows he became entangled with Dion’s body and a cave line. Heavy breathing led to rapid CO2 buildup in his rebreather, causing loss of consciousness and death (45:58).
• Don describes reviewing the footage:

  “We followed it through breath by breath... you could hear on the genuine tape, you can hear the breaths.” (Don Shirley, 45:58)

9. Living with the Consequences

• Physical Recovery: Don undergoes intense physical therapy but never fully regains his balance—still, he returns to diving (47:52).
• Outlook and Philosophy:

  “There was absolutely at no point on that dive did I ever think that I wasn’t coming back... If you believe you can, you can do it.” (Don Shirley, 48:52)

• He reflects on Dave’s legacy:

  “Died with his boots on. Died doing what he loved and what he wanted to do... just like I'm expecting him to come around the corner...” (Don Shirley, 49:53)

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Notable Quotes & Memorable Moments

• On Cave Depth:

  “At this point, more people have walked on the surface of the moon than have ever successfully dived to these sorts of depths.”
  (John Hopkins, 03:02)

• On Extreme Darkness:

  "You're actually in the darkest of blackest of places that actually eats your light. The light just disappears, it just evaporates. It's like the cave is eating it up. It's a dark, dark place."
  (Don Shirley, 07:01 & 23:25)

• Mantra for Survival:

  “The surface is not an option.”
  (Don Shirley, 12:47)

• On Facing Crisis:

  “All I had to do was what I do and I would work my way out. So even at the point where I was adding the gas to breathe or when I was throwing, I was never thinking, oh, I need to get out. All I was doing was living where I was.”
  (Don Shirley, 48:52)

• On Loss and Legacy:

  "In the army, we used to say, died with his boots on. Died doing what he loved and what he wanted to do. So, you know, in that is a good death, that's the way that I always look at it."
  (Don Shirley, 49:53)

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Timeline of Important Segments

| Timestamp | Key Segment | |------------|---------------------------------------------------------------------------------------------------------------------| | 00:58 | Introduction, Bushman’s Hole described | | 02:51–05:34| Discovery of Dion Dreyer’s body / Decision to recover | | 06:40 | Philosophy of deep dive survival | | 10:33–12:47| Don Shirley’s diving background, love of the deep | | 14:53–17:30| Formation of Don and Dave’s partnership / First dives together | | 18:05–21:04| Detailed recovery mission planning, logistics, rules | | 23:25–26:02| Descent into Bushman’s Hole, first signs of trouble | | 27:12–30:05| Equipment failure, critical decisions, Don's near-fatal rebreather malfunction | | 35:12–38:21| Don’s blackout, disorientation, and survival instinct | | 40:33–43:24| Support and rescue, physiological collapse, decompression, and extraction | | 44:54–45:58| Recovery of the bodies, analysis of the accident, helmet cam footage explained | | 47:52–48:52| Don’s physical and psychological rehabilitation; key lessons and positive philosophy | | 49:53 | Remembrance of Dave, finding meaning after tragedy |

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Episode Takeaways

• Technical mastery, experience, and friendship are critical to undertaking extreme explorations, but the risks of deep cave diving can never be fully mitigated.
• Human resilience and ingrained training can make the difference between life and death, as illustrated by Don’s automatic responses under dire conditions.
• Sacrifice and legacy: Dave Shaw succeeded in recovering Dion Dreyer’s body, fulfilling his promise, even at the ultimate price. Don Shirley’s reflections honor both the tragedy and the enduring spirit of adventure and camaraderie in the diving world.

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This episode stands out for its vivid descriptions, personal insight, and sobering exploration of what it means to confront danger, loss, and survival beneath the earth’s surface. For those interested in extreme adventure, technical diving, or the limits of human endurance, it is a must-listen.

Transcript

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[Narrator (John Hopkins)]

It's Thursday, Oct. 28, 2004 in South Africa. The undulating plains of the Kalahari Desert stretch out beneath a pale sky, the ochre colored earth and scrub brush warmed by the brilliant sunshine. But in an isolated corner of the country's Northern Cape Province, this vast rolling expanse is suddenly interrupted, punctured by an enormous sinkhole. As if a titan's fist has punched through the landscape, leaving a deep gaping wound in the ground. The walls of the abyss plunge down towards a small duckweed covered pond below. At first sight there is nothing remarkable about it, but beneath the surface this pool opens up into a spectacular bell shaped chamber, a submerged natural cathedral. This is Bushman's Hole, one of the largest freshwater caves in the world. Nobody is entirely sure how deep it may go. No light or sound penetrates its depths. It is an inhospitable alien place, a dead zone. And yet today, life has come to Bushman's Deep. Below the surface, a tiny pinprick of light descends steadily through the infinite darkness. It's a torch belonging to 50 year old diver Dave Shaw. He glides gracefully downwards with single minded focus, guided by a weighted shotline. At around 260 meters or 850ft, Dave reaches the silty sloping bottom of the chamber.

[Don Shirley]

And then he did something that no one has ever done at those sort of depths. He got out a reel, joined it to the line and started to reel out down the slope.

[Narrator (John Hopkins)]

Dave pushes deeper into the unknown, keen to explore the uncharted floor of the cave. He has just achieved an elite status. At this point more people have walked on the surface of the moon than have ever successfully dived to these sorts of depths, he is now nearly as deep as the Eiffel Tower is tall. Dave swims slowly forward, sweeping his torch from side to side. Only the third diver in history to reach the bottom of this extraordinary cavern. But then his light catches on something unexpected and shocking.

[Don Shirley]

So he's reeling out and he actually had gas that would have taken him to 300 meters. But at 270 meters, he saw a.

[Narrator (John Hopkins)]

Encased in scuba diving gear, the body is lying on its back, its legs outstretched, its arms floating exposed to the water. Its head and hands are mere bone. Yet a diving mask is still strapped disquietingly to its skull. The face turned up towards the black void above. Barely hesitating, Dave abandons his exploration and swims towards the body. He wraps his arms around it and tries to lift it from the silt, but it won't budge. Already over his maximum time at this depth, Dave has no choice but to turn and begin his long, treacherous journey back to the surface. But not before attaching his cave line to the body so that it can be easily found again. At around 140 meters, he meets his close friend and frequent dive partner, 48 year old Don Shirley, who has been acting as his support. Today, Dave manages to communicate what he has found and Don gravely acknowledges. He shakes his friend's hand, then leaves Dave to continue his ascent to the surface. But they will both be coming back here soon. Wordlessly, almost telepathically, a decision has already been communicated between them. What neither man can know is the unimaginable impact this decision will have on so many lives. Or the tragically high price which will be paid as a result.

[Don Shirley]

We then mutually decided without words, we would actually go down and pick up the body in a couple of days time.

[Narrator (John Hopkins)]

Ever wondered what you would do when disaster strikes? If your life depended on your next decision, could you make the right choice? Welcome to real Survival Stories. These are the astonishing tales of ordinary people thrown into extraordinary situations. People suddenly forced to fight for their lives. In this episode we meet world renowned diver don Shirley. In October 2004, Don and his friend Dave are diving in South Africa's legendary Bushman's Hole. When Dave stumbles on a body in the darkest depths of the flooded cave. The discovery kickstarts an audacious mission, the deepest body recovery ever attempted. But in this environment, there is almost no room for error. Even the slightest mishap can be fatal.

[Don Shirley]

When you're deep, really, only you can solve your problems. Only you can breathe for you. Only you can swim for you.

[Narrator (John Hopkins)]

So when during the dive, the two friends run into multiple unexpected difficulties, a harrowing battle for survival ensues in one of the most hostile and perilous places on earth. And the consequences will be calamitous.

[Don Shirley]

You're actually in the darkest of blackest of places that actually eats your light. The light just disappears, it just evaporates. It's like the cave is eating it up. It's a dark, dark place.

[Narrator (John Hopkins)]

I'm John Hopkins from the Noiser Podcast Network. This is Real Survival Stories. It's 4am on Saturday, Jan. 8, 2005 in South Africa. The skies above the Kalahari desert are still black, the landscape cloaked in the blanket of night. Inside a small lodge on Mount Carmel Game Farm, some 300 miles southwest of Johannesburg, an alarm breaks the silence of a dark room shared by two men, 48 year old Don Shirley and 50 year old Dave Shaw. The two friends stretch and yawn, then set about the business of showering and getting ready for the day ahead. Their actions are ordinary, offering no hint of the vast undertaking that lies ahead of them. After a light breakfast, the two men climb into Don's pick up truck and pull away from the lodge. In the pre dawn darkness, they drive east through the desert, their vehicle bouncing along the rough dirt track. Their destination is Bushman's Hole, one of the largest and most dangerous freshwater caves on the planet. It has a known depth of around 280 meters, over 900ft, but could go even deeper.

[Don Shirley]

The cave, when it goes down, is a big sinkhole. We don't really even today know where the bottom is or how deep it really is. People have been to what is the bottom that you can actually easily get to. But I'm sure it goes further.

[Narrator (John Hopkins)]

But Bushman's Hole is legendary in the diving community for more than just its depth. In December 1994, tragedy struck. A 20 year old diver named Dion Dreyer died in the cave after losing consciousness around 50 or 60 meters down. His body was never found until nearly 10 years later when Dave Shaw stumbled upon him frozen in time on the cave floor. And today, after months of planning, Dave, Don and a team of other divers will try to recover Dion's body and return him to his family. It's an ambitious project, but if anyone's up to the task, it's these men. Though incredibly, Dave only learned to dive in 1999, he has achieved meteoric success, rising in a handful of years from a novice to one of the world's most skilled and audacious divers. Don, meanwhile, has been at this for decades and is a respected, well known instructor with a wealth of experience. Raised in Egham, near London, Don's passion started at the age of 10 after a visit to Wookie Hole in southern England. An impressive cave system featuring a number of underwater chambers and tunnels. Young Don was entranced.

[Don Shirley]

I thought, wow, I just, just want to go and look underneath here and see where it goes, see what it does. So that's really where the, the quest for diving and then cave diving really started.

[Narrator (John Hopkins)]

However, diving was relatively niche in Britain at the time. Information and instruction were difficult to find and equipment expensive. Nonetheless, Don was determined. After leaving school, he joined the army, which gave him the opportunity to learn to dive and try other adventure sports, such as gliding and parachuting.

[Don Shirley]

I did diving almost from day one. I spent half my time in the evenings doing diver training and things like that. And we'd go away on weekends eventually. The Sergeant Major used to think that I was trying to get away from doing duties on a weekend, but I was actually going diving. Diving was my absolute passion and I really carried that on throughout my time. So anytime I could, I went diving.

[Narrator (John Hopkins)]

Don's career in the military took him across the globe, from Northern Ireland to the Falklands and the Persian Gulf. Alongside his military duties, he racked up thousands of dives. And as he honed his skills, he began passing on the knowledge he acquired to others. After retiring from the army at the age of 40, Don was able to focus on his true passion. He moved to South Africa and set up a diver training center in a flooded multi level mine named Kamati Springs. For divers, it's a paradise of flooded passageways, deep shafts and old mine workings. Together with his wife, Andre, Don has built a thriving business. Among his specialties is his pioneering use of rebreathers, machines which recycle the gas breathed by a diver instead of expelling it into the water. Like more traditional open circuit systems, rebreathers allow divers to remain at greater depths for longer periods of time without needing to carry numerous large gas cylinders. However, due to the contraption's complexity, there is greater potential for malfunctions. Still, for Don, this tech is liberating.

[Don Shirley]

When you're going in water, you exist at another level. Everything becomes very, very focused. And really that's one thing I like about diving in general. It's just the fact that when you're in the water, you're no longer a surface dwelling creature. You actually live in the water, which is really one of my mantras. When you're diving, you're living in the water just like a fish would live in the water. And you never look at the surface as being somewhere to go. My bet saying is surface is not an option.

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[Narrator (John Hopkins)]

Don's reputation as an instructor quickly spread. Among those drawn to his dive center was Australian pilot Dave Shaw. Although relatively new to the activity, Dave has already completed a number of impressive dives by the time he visited Kamati Springs in September 2002. And what he lacked in experience, he more than made up for in ambition and ability. During Don and Dave's first dive together, it was clear this was the beginning of something special.

[Don Shirley]

We felt like we knew each other quite well. I watched him kit up and he kitted up just like I would. It very much fitted in with my profile of diving with people. Anyone can turn up to me and give me a whole list of qualifications, but until you actually get them in the water, you don't really know what they're going to do. So the first dive always is the checkout dive and then you gradually extend from there. But when Dave joined me, it felt like he'd been diving with me forever.

[Narrator (John Hopkins)]

As Their time in the water together increased, so too did their friendship. A deep, almost brotherly bond soon formed between the two men. They even looked similar enough that they were frequently mistaken for siblings. Crucially, they were equals in the water, able to dive together to extreme depths where few could follow.

[Don Shirley]

We literally played in the water. I used to call it a ballet where he would go one way, I would go another. And we used to meet in the middle somewhere. My cave is like a three dimensional maze, so you can literally go in all sorts of directions and meet up if you know what you're doing and where you're going. So really that's what we did. One day I would lead, another day Dave would lead. We used to call it Batman and Robin. Everything we did was just a pleasure. It wasn't about depth. What it was about was actually using the equipment that we were using to the end of its ability to really put the machines through their paces and actually enjoy being there.

[Narrator (John Hopkins)]

It wasn't long before Don knew Dave was ready to tackle something more challenging than Kamati springs. And in June 2004, they visited Bushman's Hole together.

[Don Shirley]

That was the start of Dave's adventures at Bushman's. And it's a poetic place. It's one of the Big five, or what I call the Big five Ks of Africa. And each one comes with its own thing, but they're all deep. But we were actually exploring the depth in a big open space that is pitch black but bright. When we shine our lights on it, it's just an amazing place to go. So Davis hooked him

[Narrator (John Hopkins)]

on their second visit to Bushman's in October 2004. With Don acting as his support diver, Dave became only the third person in history to return from the floor of the cave and set a world record for depth on a rebreather in the process. What nobody could have known was that he would also find DeAndrea's body. Both Don and Dave naturally assumed they would repeat the dive in the coming days and recover the body. But things haven't been that simple.

[Don Shirley]

Obviously, straight away, the news came out that the body was in the water, and now it turned into a crime scene because this is a body in the water and it needed to have chain of evidence and everything else. So it reasonably quickly became, no, we can't just turn around in a couple of days time and casually fly, dive and go and pick up the body

[Narrator (John Hopkins)]

and bring it out instead. The last two months have been focused on coordinating and planning one of the most daring body recoveries. Ever attempted. The logistics alone are daunting.

[Don Shirley]

We had to put everything in place to do a body recovery dive, which is a completely different animal to doing a normal dive where you're just diving for fun. Bushman's is not a little puddle that you'd actually wander into. It's actually in the middle of nowhere. You're six hours or maybe nine hours from Jo', Burg, Johannesburg, and there are no facilities there for a diver, so you have to take everything.

[Narrator (John Hopkins)]

It's a massive operation and takes nearly a week to get everything on site, to make final preparations, and to perform practice dives. By the time Don and Dave park up at Bushman's Hole on the morning of January 8, 2005, the place has been transformed. Tents and vehicles litter the rim of the abyss. The air thrums with the sound of a generator, and people hunch around campfires. In addition to support divers and medics, there are police, reporters, a documentary film crew, and a mine rescue team. There is even a mobile recompression chamber on site, crucial for any diver who may suffer decompression sickness or the bends as they surface. Scuba gear is scattered on the boulders around the pool near a multitude of gas cylinders piled on the rough ground. As the world lightens, people pick their way down the rocky slopes and begin preparing for the dive. On paper, the plan is simple. Dave will swim down to the bottom of the chamber and place Dion's body into a specially designed silk body bag. As he ascends, Don will be diving down to meet him at 220 meters, around 720ft, where he will take possession of the body. Don will then rise through the water and pass it to the next support diver and so on. The relay process will continue until the body reaches the surface, thereby freeing up the divers who have been deepest and need to complete the longest decompression stops.

[Don Shirley]

We had a whole team of divers. Everybody there was doing an epic dive in their own rights, all diving effectively solo within a team moving through water column. So everyone is doing an incredible dive.

[Narrator (John Hopkins)]

There are some clear rules. If anything goes wrong, each person is to prioritize their own safety. There are to be no heroics, and Dave and Don both publicly state that if they perish during the dive, they do not want to be recovered on the surface. The team will be coordinated by a dive marshal, Werner van Schaik, who set the women's world record for deepest scuba dive at the site just days before Dave discovered Dion's body. If all goes to plan, the process should run Like a well oiled machine. But despite all their preparations and precautions, when entering such a hostile environment, the slightest problem could have catastrophic ramifications. Shortly after sunrise, everything is in place.

[Don Shirley]

We go down early morning because we're doing a 12 hour dive, so we want to dive early so that we can finish the dive still in daylight. So at six o' clock we are ready to dive. Dave's in the water with all his gear, with his helmet on, with the camera. And this is well, well, well before GoPro. This is a monster on his head. So he's got this camera which he turns on, on the surface. I get in the water with him before he goes because I want to show him that I'm ready to go because he needs to know that I can follow. So we shake hands and he goes down.

[Narrator (John Hopkins)]

Just after 6am, Dave sinks out of sight beneath the water. The focus then turns to timing the next diver's descents. Don floats in the pool as the seconds slink by, staying calm and focusing on his breathing. 12 and a half minutes after Dave goes down, Don follows him. He makes for a narrow opening at the bottom of the pool, a bottleneck which eventually opens up into the enormous chamber. As Don descends, the slanting shafts of sunlight start to fade and he enters a twilight zone. The blackness closes in as he emerges into the upper section of the vast underwater cavern. His torch illuminates the astonishingly clear water around him. But the chamber is so large and so dark that the beam of his light doesn't touch its rocky walls.

[Don Shirley]

You're actually in the darkest of blackest of places that actually eats your light. The light just disappears, it just evaporates. It's like the cave is eating it up. It's a dark, dark place.

[Narrator (John Hopkins)]

Many would recoil from such places, but Don is at home. There is a serenity here. His bulky equipment, so cumbersome on land, now seems weightless and he glides gracefully through the water. Around 120 meters down, Don begins looking for signs of Dave, who should at that very moment be returning with Dion's body. The darkness below offers few clues as to what is happening now.

[Don Shirley]

As I'm dropping, I'd expect to see bubbles from Dave, because you don't make bubbles in a rebreather, but when you're coming up you do, because gas expands and you have to vent that gas off.

[Narrator (John Hopkins)]

But there are no bubbles. It's possible that Dave has been delayed at some point during his descent or whilst securing the body inside the bag. But as Don continues down the shot line and still sees nothing. Concern mounts. He goes another 10 meters, then 20, and still there is no sign of his friend.

[Don Shirley]

I expect to see some bubbles, see something going on below me. I don't see anything. So then I think something is. Something's wrong.

[Narrator (John Hopkins)]

Don squints into the dark abyss below, looking for any indications that Dave is on his way back up. At a depth of 150 meters, nearly 500ft, he passes a last cluster of emergency gas cylinders that had been clipped to the shot line. And then suddenly, he sees something. A tiny light shines in the darkness more than 100 meters below, like a single star burning in the vast blackness of the night sky.

[Don Shirley]

I look down and I can see a small, small, small light in the distance. And the agreement that Dave and I had is, if you've got a problem, the distress signal is waving a light. The intention was if he had a problem, he would wave the light, I would carry on down. I had the gas to do it. I was the only diver that actually could go to those depths. Everyone else had limits.

[Narrator (John Hopkins)]

But the light isn't moving as don descends towards 220 meters, the intended rendezvous point with his friend. It remains motionless and still. There are no bubbles to suggest Dave is ascending. In the gloomy depths of the cave. Something has gone badly wrong. Don has to get down there.

[Don Shirley]

As I'm going down, I'm going right, okay, I'm probably going to go all the way down, so I'm preparing for that fact.

[Narrator (John Hopkins)]

He continues plummeting through the fathomless darkness, the pressure increasing with every meter he descends. The light grows bigger as he nears it, but it remains unmoving. With steely calm, Don pushes on towards the bottom of the cave. 230 meters. 240. He is now deeper than he has ever been before. And then, at about 250 meters, there is a sinister crack, followed by a dull th. To an expert like Don, it's a grimly familiar sound.

[Don Shirley]

Now, I've heard that thud before where you're at depth and you get an implosion of some sort. It's not an explosion, it's an implosion. So you get a. Almost like a sucking thud. And you feel it in your body because in the water you can feel all these things. So now I had to put the brakes on.

[Narrator (John Hopkins)]

The rebreather controller on his left wrist has imploded under the immense pressure. At this depth, things have just got a whole lot more complicated. Don must now manually insert gas into his breathing apparatus using another controller and It's a tricky task at these depths. Too much oxygen becomes toxic and can cause severe convulsions, which would likely prove fatal.

[Don Shirley]

What I do is I add a little bit of oxygen. It's a drill that we practice many, many times, but I've never put oxygen in. At 250 meters, the display on the handset jumped up to 2.6 bar pressure of oxygen, which is really unhealthy.

[Narrator (John Hopkins)]

Even as he tries to delicately feed oxygen into the system, the levels of the gas in his rebreather grow dangerously high. Don is forced to switch to his open circuit backup tanks. But that comes with another problem.

[Don Shirley]

The first thing you do when you go open circuit is look at the gauge to see how much gas you've got. Now when you look at the gauge, just like a second hand on a watch, with every breath it clicks back like a second hand going backwards. So I knew that I didn't have many breaths at that depth. I'm 26 bar pressure. So 26 bar pressure is every breath is multiplied by 26, so that gas is not going to last too long. So now I've got to get off this open circuit.

[Narrator (John Hopkins)]

Back to plan A. Don needs to get his rebreather stabilized soon. If he can't, he may not have enough gas in his backup tanks to reach the nearest emergency cylinders nearly 100 meters above. Drawing on his years of training, he performs a procedure known as flushing the loop, reducing the oxygen in his rebreather to safe levels so he can switch back to the machine. Slowly, he gets things under control. Crisis averted for now. But manually inserting gas and monitoring his levels is going to be a full time job. All his attention now has to be directed towards his own self preservation. And if he is having to focus on himself, it means he cannot focus on Dave. He cannot go any deeper. The bleak situation leads to a painful decision.

[Don Shirley]

Now I know there's absolutely no way that I can go down to Dave and Dave's not moving. So this is in priming terms, this is where you'd cut the rope. So now I must leave. But all the time I'm thinking, Dave is not dead to me here. Maybe something will happen. Maybe he'll be able to come out, maybe I'll be able to follow along, but I've actually got to come up now.

[Narrator (John Hopkins)]

With one last glance at the unmoving light of his friend, Don begins to head back to the surface. Having gone deeper than he planned, he now needs to work out a new schedule for his ascent to Limit his chance of getting the bends. Also known as decompression sickness. This occurs when a diver resurfaces too quickly, not allowing enough time for nitrogen, another gas absorbed into the body through breathing to be safely released. Without proper decompression stops, the nitrogen can form highly dangerous bubbles in the blood and tissues, leading to dizziness, difficulty breathing, and even paralysis. Above, Don right now is almost 250 meters of water, over 800ft. It's going to be a long, dangerous journey. On the surface, everything is running smoothly. Nobody has any idea of what has just happened in the depths of the sinkhole. As planned, the next support divers enter the water and descend to 150 meters, where they are scheduled to meet Don. But when they get there, he's nowhere to be seen.

[Don Shirley]

I've got divers waiting at 150 meters, but I knew they wouldn't be there and when I got there, because they can only stay so long. And the command is, stay as long as you are programmed to stay and then leave. Because what we don't want is multiple injuries. We don't want someone to sacrifice themselves unnecessarily for somebody else.

[Narrator (John Hopkins)]

Just before they have to leave, the two support divers see a single light rising up through the darkness. At this distance, they have no idea whether it belongs to Dave or Don, but its significance is clear. Only one of them is coming back. The divers retreat to the surface to break the news to the rest of the team. Meanwhile, Don continues his slow, steady ascent, all the time looking back down to see if there is any movement from Dave's light, clinging to the unlikely hope that his friend might still be alive. Eventually, he reaches 150 meters, where a group of emergency tanks are clipped. With the gas in his own cylinders, now depleted after his rebreather malfunction, he's reached them at a crucial time.

[Don Shirley]

I come up, I get to that 150 meter, no bubbles below, light, still not moving. I'm on my own there, and what I should do is actually pick up another cylinder. I've really only got one and a half cylinders if something went wrong. But now I don't take the cylinder. I leave the cylinder for Dave. If Dave comes back, he's going to need the gas. So I leave the cylinder there and I carry on out.

[Narrator (John Hopkins)]

It's an unrealistic shred of hope, but hard to shake on the surface. Dive Marshal Werner has set an emergency plan into motion, and tension mounts as people wait to discover which diver is coming back. The question is soon answered. When Don reaches 80 meters, another support diver drops level with him. Immediately, the diver sees Don's wrecked rebreather controller. It's obvious he has gone deeper than planned, and that can only mean there was a problem. Don goes to write something on a diving slate, a plastic waterproof tablet divers can scribble on to communicate underwater. It is vital that the rest of the team knows what has happened so they can adjust their plan accordingly.

[Don Shirley]

I write on a slate and say, dave's not coming back. So I give that slate to him and I say, don't go down, go up.

[Narrator (John Hopkins)]

The dive has turned tragic, but there is little time now to process it properly. All attention switches to getting Don out safely and ensuring there are no other accidents. In the dark embrace of the cave, Don focuses on keeping his oxygen levels under control and adhering to the correct decompression stops. At around 45 meters, he reaches the roof of the enormous chamber. Somewhere above him is the bottleneck which will take him back into the basin above. Don reaches for another nearby cylinder attached to the line so he can flush his breathing loop and maintain safe levels of gas within his rebreather. But then, with no warning, Don's surroundings suddenly turn hazy and unsteady. His eyes struggle to focus. He is losing consciousness.

[Don Shirley]

I pick the cylinder up and clip it off onto me. And as I do that, I start to pass out. It's like I'm not there. I've just mentally drifted away. It's like I'm fainting, like I'm going to sleep, but I'm in a dream world. I don't even know where I am.

[Narrator (John Hopkins)]

With the edges of his vision darkening, Don has just seconds before blacking out completely. If he does, he'll drown. Don's movements become automatic, mechanical as his ingrained training and muscle memory take over. Divers using rebreathers are taught to change instantly to their open circuit backup tanks if they sense themselves starting to lose consciousness. Don has practiced the training drill enough times and taught it to hundreds of students. But this time it's for real.

[Don Shirley]

I do it completely by remote, completely without command. I just do it. Just like you would do when you're driving a car and you need to stop the car in an accident. So I did it without even thinking.

[Narrator (John Hopkins)]

Don's mouth closes around his scuba regulator and the gas flows into his lungs. But then the world begins to spin. His vision blurs as he starts to rotate through the water. There is no knowing which direction he's facing or which way he's moving. He isn't aware of this now. But when Don switched to open circuit, a tiny bubble formed in his left inner ear, completely disrupting his sense of balance and causing severe vertigo. He tumbles through the water, completely disorientated, pinwheeling helplessly in a void.

[Don Shirley]

Now I'm spinning around like a top inside this cave. I've got about 250 meters of water below me at this point. Point. Not that that's actually going through my head, because I don't even know what planet I'm on at that point. So I'm underwater and I'm going around, and I'm on the roof, and it's a black roof, but I've got bright lights, so when the light hits the roof, it's, like, white. And when I carry on spitting, it goes into the black. So the light is going black, white, black, white as I'm going around.

[Narrator (John Hopkins)]

The sensation is surreal. Extreme darkness and extreme brightness flashing through his vision. With no control over his movements and no sense of direction, the biggest risk is that Don will spin off into the black infinity of the chamber, away from his shot line. And if that happens, he'll be lost in the chasm, unsure of which way is up or down. As he twists, something flashes across his eyes. It's his shot line, briefly glimpsed in the water. As he comes back around, he takes his chance. The shot line appears again, and he makes a desperate, instinctive lunge towards it. A second later, his fingers close around the weighted rope.

[Don Shirley]

I managed to basically hook onto the rope, otherwise I just kept on spinning and going out of control and disappearing to the depths of. So I hold onto the rope and I spin around the rope, and this is all in a dream. I'm not thinking it's just by instinct.

[Narrator (John Hopkins)]

Don hangs on with all he's got, but the grip doesn't stop his motion, and he continues to twist and flail. It's a crazy, confounding blur. Finally, he slows, his tight grasp on the lifeline still intact. Taking a moment and regaining some of his clarity, he is able to look at the dive computer attached to his wrist, which tells him his depth. Somehow, in his barely lucid, discombobulated state, he has still managed to travel upwards along the rope. But he is at 35 meters. He has gone too high too quickly. He has to get his decompression schedule back on track. Moving carefully, Don retreats down the line to 46 meters. Now, totally unable to focus properly on his rebreather's controls, his safest option is to stay on his backup Open circuit tanks. But this will burn through his air supply and with the time consuming ascent still ahead of him, is going to need more gas. Don reaches out for a cluster of cylinders clipped to the line nearby. As he does so, his stomach does a somersault.

[Don Shirley]

So now I find every time I move, I vomit. Anytime I do anything, pick a cylinder up and clip it off, I vomit. I'm on open circuit and if you vomit, you tend to take the regulator out of your mouth, vomit, and then put it back in, clear it and carry on breathing.

[Narrator (John Hopkins)]

When he is finally able to, he gingerly starts grappling his way up the line towards the next decompression stop. Above, a figure moves down towards him. A support diver is coming to check on his progress.

[Don Shirley]

He's coming down to see how I am. When I write on a slate, I'm having a hard time, nausea and vomiting and I have to write it like that so they can't misconstrue what I'm saying. I've come out of that dream and I can control what's going on, but I can't move my body. I can't get my legs into the place that I want to be. I can hold onto the rope, but I can't get myself horizontal. I can only stay where I am. And anytime I try and do something, I spin.

[Narrator (John Hopkins)]

Rapidly. The news reaches the surface team. Don needs urgent aid. A tether is made to clip him to the shot line in case he loses consciousness. And a rotor is agreed to ensure at least one diver remains with him at all times. But despite this, Don's situation remains dire. It's been a couple of hours since he entered the water, but as he nears the surface, his decompression stops need to become longer and more frequent, meaning he still has more than 10 hours to go. The climb is grueling. Don's throat and stomach are raw from retching and it takes all his strength to maintain his grip on the shot line. But even as he edges laboriously closer towards the light and air, this strength is fading. Too weak and dizzy to maintain a diver's usual pal horizontal position, which allows gas to flow directly into the lungs, Don is forced to breathe vertically. Soon every inhale is a painful effort.

[Don Shirley]

As I got closer to the surface, I was getting to the point where I couldn't breathe anymore. Normally, when you're in the water, you want it to be horizontal if you suck gas in. And when you're in the vertical position, you have to use all your muscles to actually bring it down. So the intercostal muscles in the diaphragm are working with every breath to really suck the gas down. And it's getting to the point now where I couldn't breathe.

[Narrator (John Hopkins)]

Don is forced to press his regulator's purge button with each inhale, which helps to push a stream of gas into his lungs. It's all that's keeping him alive. And then when the surface is tantalizingly close, there is another problem. He's struck by a new, terrifying pain. A sharp stab in his left knee, a classic sign of the bends. There's no more time. After some negotiation with the medics, Don agrees to cut his decompression in the water short and take his chances on dry land. And so, 12 and a half hours after beginning his dive, he finally lets the team pull him from the water and into the warm evening air.

[Don Shirley]

I just give myself over for them to control. I just let myself go and be taken care of. And I saw video of me. I looked like a real mess when I got out the water.

[Narrator (John Hopkins)]

Utterly depleted and unable to walk, Don is placed on a gurney, then hoisted up the slopes with a rope and pulley system and taken to the mobile recompression chamber above. He has made it out of Bushman's hole, but that doesn't mean his battle is over. He remains in the claustrophobic, oxygen rich chamber until the early hours of the morning. When he is eventually able to emerge, it becomes clear quite how serious his condition is.

[Don Shirley]

I couldn't walk unless I had someone to lean on. My eyes were crossed, I couldn't see properly, I couldn't balance in any which way. I could still talk and I could still think, but that was about it.

[Narrator (John Hopkins)]

Before he collapses in his bed, Don is briefly able to phone his wife, Andre, who has been kept informed of his situation throughout the day.

[Don Shirley]

I spoke to Andre and our standard greeting after any dive is, I'm alive. So that's what I said to her on the phone, I'm alive. And when I spoke to her at 3 o' clock in the morning, she left where we are and did the 12 hour drive to Bushman's to come and see me. So that was the start of yet another journey, really, of getting better, and it took a long time.

[Narrator (John Hopkins)]

In the midst of the grief around Dave's death, there is one central question. What went wrong? As it turns out, it isn't long before an answer is revealed. In the days following the accident, some of the team begin retrieving the lines and gas cylinders that remain in the chamber. As they pull the shot line up, the movement dislodges Dave's body from the bottom of the cave, and he floats up towards the surface. And suspended below him by a thin cave line tangled around Dave's scuba gear is Deondrea. After the bodies are retrieved, attention turns to the camera Dave was wearing. The footage shows his dive went entirely to plan until he tried to place Dion into the body bag, at which point both he and the body became unexpectedly ensnared in the cave line. During the struggle to free himself from the tangle, Dave's breathing grew heavier, increasing the amount of CO2 he was emitting into his rebreather.

[Don Shirley]

So the CO2 buildup basically knocks you out. So what we believe is that the CO2 buildup in his body put him to sleep, so he wouldn't have known what was going on any more than I would have known when I was spinning around at 46 meters. Now, we've looked at that tape and we followed it through breath by breath, and I found myself breathing the same way or breathing with Dave, because you could hear on the genuine tape, you can hear the breaths.

[Narrator (John Hopkins)]

As Don reckons with the loss of his friend, he is also struggling with his own physical recovery. The effects of his decompression sickness are so bad that it's feared he may never walk normally again, let alone dive. In the days that follow, he endures several sessions in the recompression chamber before Andre drives him for further treatment at a hospital in Pretoria. Though Don shows incremental improvement after each session, progress is dispiritingly slow.

[Don Shirley]

So each treatment I did, I got about 50% better with each time, but I still had a big problem with balance. I couldn't walk in a straight line. I could walk unsupported, but I couldn't walk in a straight line. I couldn't walk at night in the dark, I had to crawl. So if I wanted to use the toilet at night, I had to crawl. I'd hold conversations and I would have to concentrate so much on what I was doing, I'd actually forget the conversations.

[Narrator (John Hopkins)]

Yet despite his debilitating symptoms, his determination to get back to diving propels him forward. Only a matter of months after the tragic events at Bushman's Hole, he tries re entering the water at Kamati Springs for the first time.

[Don Shirley]

I didn't even know if I could dive at that point, so I went into the water and found that I actually felt better in the water than I did on the land because I'm an aquatic person, you know, So I felt better there because I could actually sense things. But I still can't even now swim in a straight line. Even today, I still have a problem with balance. This is a problem I'll always have. So I've lost balance really, in the left side, not completely, but what happens is you get used to dealing with it. So now I've. I'm doing things. I'm running up and down all over the place and doing all the dives I ever used to do. I consider myself, you know, recovered after that first year, really, in terms of diving. But in practical terms, there'll always be damage.

[Narrator (John Hopkins)]

Despite everything, Don has returned many times to dive at Bushman's. In the years since the accident, he's had plenty of time to reflect on his near death experience there and on what enabled him to survive.

[Don Shirley]

What I came to realize on that was there was absolutely at no point on that dive did I ever think that I wasn't coming back. There was never even a question in my mind. All I had to do was what I do and I would work my way out. So even at the point where I was adding the gas to breathe or when I was throwing, I was never thinking, oh, I need to get out. All I was doing was living where I was. So now one of my things is I say, you know, believe you can, because if you believe you can, you can do it.

[Narrator (John Hopkins)]

In the end, Dave did fulfill his promise to recover Dion's body, though he paid the highest price imaginable for it. At the behest of Dave's widow, Don scattered his friend's ashes near his home at Kamati Springs, the place where they first dived together and where two decades later, Don continues to dance in the water, both for himself and for Dave.

[Don Shirley]

In the army, we used to say, died with his boots on. Died doing what he loved and what he wanted to do. So, you know, in that is a good death, that's the way that I always look at it. And Dave is always in my thoughts, not in a macabre way, but just like I'm expecting him to come around the corner and we can discuss the good things that we've just done. And that's still, you know, 22 years later and so still very much on, on ongoing process. And it still dives in that sense.

[Narrator (John Hopkins)]

In the next episode, we meet mayan sabag. In 2008, the 27 year old is studying in the Chinese city of Chengdu. One day, her friend suggests they escape the hustle and bustle and head to a remote nature reserve. But while passing through a village nestled in the mountains, they suddenly find themselves at the epicenter of a terrible natural disaster. A magnitude 8 earthquake that will go down as one of the deadliest in human history. When the restaurant they're sitting in collapses, Mayan is trapped in the pitch black, buried alive and so badly injured, she's unable to even call out for help, even as she fights to free herself from this living tomb. Up above on the surface, the situation is even worse. Escaping burial is just the beginning. That's next time on REAL Survival Stories. Listen today by joining Noiser.