Documentary follows the divers who risked it all in the Thailand cave rescue

DAVE DAVIES, HOST:

This is FRESH AIR. I'm Dave Davies, in for Terry Gross. We're going to hear today about one of the most remarkable rescue operations in recent memory. The crisis began in June 2018, when a group of boys went into a long, winding underground cave in northern Thailand to celebrate one of the boys' birthdays.

(SOUNDBITE OF FILM, "THE RESCUE")

UNIDENTIFIED PERSON #1: The boys, aged between 11 and 16 years old, are all members of a Thai soccer team. They became stranded in the dark tunnels after a sudden and continuous downpour blocked all exits.

UNIDENTIFIED PERSON #2: (Speaking Thai).

UNIDENTIFIED PERSON #3: This rain is going to get worse and worse and worse as the months go by. Four months of monsoon - it'll flood out that cave system. So there will be no hope of getting out if they don't get them out very soon.

(SOUNDBITE OF MUSIC)

DAVIES: That's from the documentary film "The Rescue," produced and directed by our guests Chai Vasarhelyi and Jimmy Chin. The world held its breath for 18 days while an international team of military, civilian and volunteer personnel worked first to locate and eventually bring the boys and their coach to safety. Also with us is Rick Stanton, a retired firefighter and veteran cave diver from England, who played a critical role in the rescue effort.

Jimmy Chin and Chai Vasarhelyi are a husband-and-wife documentary filmmaking team. Chin is an accomplished mountain climber. And their film "Free Solo" won the 2019 Academy Award for best documentary feature. For the film about the cave rescue in Thailand, they use some remarkable video shot during the operation. And for some underwater scenes, they shot reenactments using participants in the events. "The Rescue" is in select theaters now and will open more widely this Friday.

Well, Chai Vasarhelyi, Jimmy Chin, Rick Stanton, welcome to FRESH AIR. Let's talk first just about the setting of this. You know, there are lots of different kinds of caves. And to understand kind of the desperate challenge that this posed, we need to understand a bit. Chai, you went to Thailand as part of the research and saw the cave. Would you just explain what this cave was like when it was dry and how that changed when heavy rains came?

CHAI VASARHELYI: Well, it's a very long, deep cave. And you know, for me, I didn't fully understand just the sheer scale until I saw it with my own eyes. And when you enter, it's incredibly intimidating. There's a darkness that kind of pulls you in. And, you know, it's hard to imagine just the silence that also you experience. And, you know, at first, it feels like you should be scared. So you're scared. But then a few minutes later, it's - just enchants. It's an enchanting experience. And you just want to keep on going deeper and deeper. I very much understand why the children went in there to play. And when I was there, it was totally dry. But there were definitely sections where you have to - you know, in order to pass through, you've got to get down in your hands and knees and crawl. And when it floods, it's basically a limestone mountain which collects water from the water table. And every year during the monsoons, like, the water table rises and the cave floods.

DAVIES: Right. So an easy walk to get into on a nice day. But when it floods, it becomes this little tunnel. And much of the path that they went in would be underwater, right?

VASARHELYI: Yes. And I wouldn't say it's an easy walk. I think it's quite (laughter) perilous. I mean, it's what we would call a no-fall zone. I could see many a people breaking a leg or an arm because, you know, you just don't understand the scale until you're in there, where the caverns, they're so high. And then there are these precipices that are - you just take the wrong step and you could fall down. So I think it's challenging no matter what.

DAVIES: OK. So they enter. They don't emerge. Their parents are frantic because the rains have come. And, of course, the parents and the authorities know that they went into the cave. They didn't come out. They have no idea where in the cave they might be. We would eventually learn how far they were from the entrance. How far was it?

VASARHELYI: It was about two kilometers. But it wasn't that they were necessarily lost - is that they got trapped on the wrong side of the water. And, you know, I think in the first few days when they were trapped, they were quite close - like, they were probably only, I want to say, a kilometer in. And then as the water rose, they had to retreat into the cave to find higher ground in order to survive.

DAVIES: OK. But two kilometers - we're talking about, you know - that's more than a mile, a lot of which divers would have to go through with oxygen tanks, right? Now, Jimmy Chin, the Thai authorities brought in the Thai Navy SEALs, this elite force, which are expert divers. Why were they simply not equipped for this task?

JIMMY CHIN: Well, I think cave diving requires a specific set of skills and actually also requires a specific set of equipment. And there really, you know, are no special forces in the world, not even the, you know, American Air Force PJs that are equipped or have that experience to cave dive. And, you know, the Thai Navy SEALs, although are trained in, you know, underwater warfare, they've just never faced anything like this before.

DAVIES: Clearly committed, courageous men - but this was something new, and therefore, I want to bring in Rick Stanton. Now, Rick, you have been a cave diver. Some would call this a hobby. It's a whole lot more serious to me than most hobbies. Do you want to just explain a little bit why it is so unique, why it's different from diving, what kind of equipment and skills you have that make it so different?

RICK STANTON: Sure. I wouldn't even describe myself as a diver. I'd say - in U.S., you have the word spelunking, which is a person that explores a dry cave. I just say that I'm an underwater spelunker. So really, it's the caving skills that's forefront to us, not necessarily the diving. Our specialty - and this is what really came to the fore in Thailand - is not just going on a dive but to carry your diving gear through a cave - dry cave - dive, surface, continue carrying your gear and progress through the cave like that. In many caves, you might involve rope work - descending ropes, climbing back out ropes - all carrying your dive gear for the bits where you have to go underwater. So that's our specialty, which we have - I personally have 40 years experience of.

DAVIES: Now, you say in the film that you've known, I think, nine fellow cave divers who have died, some of which you've had - whose bodies you've had to rescue because only another cave diver can get there. Why is it so dangerous?

STANTON: Well, the principal reasons are that you're totally reliant on artificial sources for your breathing, for your light, sometimes in extreme dives, for your heating. You might have electrical heating suits in cold, frigid waters of Europe, too. It's - everything is dependent on technology, even if that technology's relatively simple, like a demand valve. But, you know, equipment fails. And the other principal reason is - I might dive in the sea. If something goes wrong, you can just immediately come up to the surface. In a cave, if you're one mile in, like we were in Tham Luang Nang in Thailand, the only place of safety is to swim that one mile out again before you've got to somewhere where there may be air surface. So you have - there's a whole load of procedures about managing your gas, how much you've got to breathe, how much you've got in reserve. And of course, not all caves are straightforward. Some are labyrinthine. So you've got a guideline. And most people who fall foul of accidents normally have broken some very basic principles, such as not having a line to the surface or mismanaging their breathing air.

DAVIES: Right. So you run a rope - right? - essentially, so that you've always got a way back to where you came from. What specialized equipment do you have that an ocean diver wouldn't?

STANTON: So as I explained, this is, you know, quite a technical sport in terms of equipment. So we would have backups. So whilst, you know, your normal scuba diver in the ocean might have a single tank and a single regulator to breathe from, we would have a minimum of two and quite possibly more than that. So if something failed, you've always got a backup. We would have multiple lights, multiple breathing sources. Everything is backed up and planned and thought about to mitigate against anything going wrong. And more specifically, in England, where we've done most of our sort of cutting-edge diving as we were developing, the caves are very small, and we wear our cylinders on our side rather than our back. So we're uniquely streamlined for going through narrow spaces.

DAVIES: Now, the other thing about this particular cave, and I guess a lot of caves that you're in, is that you're often underwater, but it's not necessarily still or calm water - right? - and particularly in Thailand. Well, what was it like?

STANTON: When we first arrived in Thailand, the river was absolutely raging - and fast-flowing water. And John Volanthen, who was with me, and myself, are both white-water kayakers. And those sort of skills of progressing upstream in a river with a fast-flowing current were also very necessary to avoid being pinned against a rock or sucked under boulders. So it was those sort of skills we needed, plus, of course, that we were actually progressing underwater. And Chai has described the cave early on. But the majority of the cave, I've not even seen. We could not see our hands in front of our face. So we were progressing practically blind, feeling our way along and not able to see at all.

DAVIES: Rick, when you first arrived at the site, what was it like?

STANTON: Complete chaos - there were hundreds of people. There was obviously the Army there, the police. But lots of volunteer local people had all come to help. Everyone wanted to be part of it - but, I mean, without being too critical, maybe a lack of coordination of all these hundreds and hundreds of people - and so just completely chaotic. We managed to actually get through a restricted area to get away from the press and the hundreds of people just so we could collect our thoughts. And the first thing we wanted to do was go immediately into the cave and get a feel for it because it was still in the process of flooding further. And we wanted to get in as far as possible and see it before we lost so much of it underwater.

DAVIES: Now, one of the remarkable things about this story is that this happens in northern Thailand in an, I guess, a pretty remote rural area. And you were in England when it happens. And most of the cave divers who would eventually assemble to participate in this were scattered all around the world.

Chai, like, when - how did the authorities find and contact all of these cave divers? How did they know to do this?

VASARHELYI: There are a lot of kind of coincidences or fortunate events that surround this story. And one of them is that there was a local caver on the ground. And his name was Vern Unsworth. And he's British. And he, you know, had heard, and he knew of Rick Stanton and John Volanthen and their, you know, very unique skill set. And he handed a piece of paper to the minister of tourism at the time and said, you know, you have one shot at this, and you've got to get in touch with these guys. And, like, who knew? Like, who knew that then they would be able to call Rick and John, they would be able to get in a flight immediately and that Vern would have this very - like, he had very unique knowledge of the cave itself 'cause he has spent, I think, the past 20 years exploring that cave and extending its known depth and was - I think, was a valuable resource for Rick and John.

DAVIES: We need to take a break here. Let me reintroduce you. We are speaking with Chai Vasarhelyi and Jimmy Chin, a documentary filmmaking team who have made the new film "The Rescue," which is about an effort to rescue 12 young boys and their soccer coach who were trapped in an underground cave in northern Thailand in 2018. Also with us is Rick Stanton, a veteran cave driver who participated in the effort.

We'll be back to talk more in a moment. This is FRESH AIR.

(SOUNDBITE OF MUSIC)

DAVIES: This is FRESH AIR.

We're speaking with documentary filmmakers Chai Vasarhelyi and Jimmy Chin. They directed the documentary "The Rescue," about the effort to rescue 12 young boys and their soccer coach who were trapped in an underground cave in northern Thailand. Also with us, Rick Stanton, a veteran cave diver from England, who played a critical role in the rescue effort, since much of the cave was underwater - it was the water that trapped the boys and prevented them from getting out.

So let's talk a bit about finding the boys, right? When this started, nobody knew where they were. There was one chamber of the cave that you descended into where there was a huge staging area with all kinds of military and civilian personnel and generators and all that stuff.

Rick, you explored the cave. You got farther and farther into it. And as you and your fellow diver, John Volanthen, would come into a chamber where there was some air, you would immediately smell - you know, whiff the air for a smell. What were you expecting?

STANTON: On that day as we were progressing upstream - I wouldn't say we were exploring 'cause the cave had already been explored. But as we were, you know, progressing upstream, the further we penetrated into that cave, the more likely it was to find the boys and the coach. But we had no idea what state they would be in. You have to think, as we were diving upstream, maybe only being able to see a foot in front of your face, we were feeling out and reaching in case we swam past their lifeless corpses. So when we surfaced in one of the many chambers that were there, we - John and I were having a conversation and then we heard other voices, and then we saw a light. And then they came into view. And despite our pessimistic thoughts, they all were ambulant and all just walked into view in front of us. And that iconic footage is exactly as it happened in real time.

DAVIES: Well, I want to play that. This is a remarkable moment from the documentary because you and your diver, John Volanthen, had a camera with you. Let's listen to this moment in the film when you and John Volanthen surface and encounter the boys.

(SOUNDBITE OF DOCUMENTARY, "THE RESCUE")

STANTON: And then suddenly, I saw a light flash.

(SOUNDBITE OF MUSIC)

STANTON: John immediately got out the camera.

(SOUNDBITE OF WATER SLOSHING)

JOHN VOLANTHEN: (Unintelligible).

UNIDENTFIED PERSON #4: Thank you.

UNIDENTFIED PERSON #5: Thank you.

UNIDENTFIED PERSON #6: Thank you.

VOLANTHEN: How many of you?

STANTON: They're all alive.

UNIDENTFIED PERSON #7: Thirteen.

VOLANTHEN: Thirteen?

UNIDENTFIED PERSON #8: Yeah, thirteen.

VOLANTHEN: Brilliant.

UNIDENTFIED PERSON #8: Yeah, yeah.

STANTON: Believe. Believe.

On the audio, there's me saying believe. That was me trying to tell me, this is real; this is actually happening.

(SOUNDBITE OF DOCUMENTARY, "THE RESCUE")

UNIDENTFIED PERSON #8: (Unintelligible).

STANTON: Not today. We have to go. We're coming. It's OK. Many people are coming. We are the first. Many people come.

UNIDENTFIED PERSON #8: What day? What day?

STANTON: Monday, Monday. OK. But one week and Monday. You have been here 10 days - 10 days. You're very strong, very strong.

DAVIES: Wow. Our guest Rick Stanton was there when the 12 young soccer players and their coach were spotted in this cave. Rick Stanton, they'd been there 10 days. Give us a sense of the emotional effect this had on you and how it affected your sense of this mission, which you'd become involved in.

STANTON: They were all very stoic. They walked there and crouched on their haunches in front of us. In the video, you hear - I was actually - John was, like, working at the camera. I was actually counting them as they came around the corner into view. So just as he asks, how many of you are there? I - you hear me say in the background, they're all alive. And trust, that was quite miraculous, considering what we were expecting to possibly find. But as amazing a moment as that was, I think both John and I immediately moved on to the next step. OK, they're here, but I've absolutely no idea how we can get them out this - you know, that underwater journey in those conditions. It is beyond their ability and, I thought, beyond our abilities to be able to bring them out at that point.

DAVIES: Right. They're still a mile away from where you began. Did you think that you might be the only two people, the last two people ever to see these kids alive?

STANTON: I did say that at the time, so all - the whole incident was caused by pre-monsoon rains. All it needed was a day of rain, and the cave would flood to an extent that we would not be able to progress upstream to reach them again. So that was always in the back of our minds. There was a lot of fortunate events, and this was one of them. The monsoon just held off long enough.

DAVIES: So Jimmy Chin, this film that we just heard a piece of, I mean, the video went around the world, didn't it? What was the impact?

CHIN: Yeah. I think that there was, you know, a lot of euphoria. We were following it in real time as well. And that moment, you know, just as parents ourselves, was incredibly moving. You know, but we didn't understand necessarily at the time how complex a rescue would be.

DAVIES: In fact, in some ways, it kind of raises the stakes - doesn't it? - because now the world thinks, aha, you've got them. Right. But you really don't.

VASARHELYI: Well, it was a ticking clock, as Rick described earlier. It was that you were racing against time because at any moment, the rains could start again, and there would be a point where - just the divers couldn't proceed any further because too strong of a current. And likewise, they also realized that the air quality in the cave was, you know, very low in oxygen. And, you know, I think they measured it at 15.6. And, you know, firefighters won't go inside a building when - if the oxygen meter reads anything below 18.

DAVIES: It's at 18% oxygen, yeah.

We'll talk about what happens next after we take a break here. We need to take another break, and I will reintroduce you. We're speaking with Chai Vasarhelyi and Jimmy Chin, documentary filmmaking team, who directed the documentary "The Rescue," which is in theaters now. Also with us is Rick Stanton, the veteran cave diver who played a critical role in that rescue effort in Thailand. They'll be back to talk more after a short break. I'm Dave Davies, and this is FRESH AIR.

(SOUNDBITE OF AVISHAI COHEN'S "CHILDHOOD (FOR CARMEL)")

DAVIES: This is FRESH AIR. I'm Dave Davies, in for Terry Gross. We're speaking with Chai Vasarhelyi and Jimmy Chin, directors of the new documentary "The Rescue" about the efforts to find and save 12 young boys and their soccer coach who were trapped in an underground cave in northern Thailand when heavy rains blocked their escape routes to the surface. Also with us is Rick Stanton, a civilian cave diver from England who played a critical role in the rescue effort. The film about the 18-day drama, titled "The Rescue," is in select theaters now and will open more widely on Friday.

The kids were located a mile away. Divers would have to get - just to reach them, just to supply food, would have to swim this very treacherous, mile-long journey to get to them. But how to get them out was the dilemma. And Rick Stanton, one thought, was, well, why don't we just bring in tanks, give the kids some instructions and help them guide them out? You had some experience earlier in this operation when you encountered some pump workers who had gotten stranded in a chamber much closer to the exit than these boys were. And were you one of those who actually tried to guide these guys out?

STANTON: Yeah, that's correct. There was - again, John and I.

DAVIES: Yeah. Yeah. So tell us what happened when you had these grown men who you gave instruction to try and guide them through this, and you gave them the equipment. What happened?

STANTON: We encountered them in the third chamber. They'd missed the evacuation. And there were maybe three short sections of dives, each about 10 yards long, maybe only a 30-second immersion. But they'd been trapped for 24 hours, so they were clearly keen to get out. But you know, most of them are non-swimmers, not confident in water.

And I basically describe the whole experience as an underwater wrestling match. As keen as they were to get out - we put a regulator in their mouth, we held them and guided them - but they were not comfortable underwater. And it sort of led, certainly in one case, to complete, blind panic, where he was just flailing around and trying to get away and actually managed to get away, but there was air above him. So we realized that, you know, these are grown men. They're very keen to get out. It's a fraction - a tiny fraction - of the distance the boys were going to have to travel. And it just wasn't going to work, just diving someone out in those conditions.

DAVIES: So a thought arose - I don't know who thought of this - but of sedating the young boys and then taking them out so that they would be passive, so that skilled divers such as yourself could guide them through and they wouldn't resist. And there's another cave diver named Richard Harris. He was in Australia. Is that right?

STANTON: That's correct, yes.

DAVIES: And he was a doctor. And you posed this idea of this. What about doing it? And this is a clip from the film where Richard Harris - this doctor - when told about how about sedating the boys and pulling them out, thought it was ridiculous. Here's part of what he said.

(SOUNDBITE OF FILM, "THE RESCUE")

RICHARD HARRIS: I could think of 100 ways a child would die very quickly. For example, to maintain your airway, you know, you need to keep their chin up. At any time during the dive, the child's airway could obstruct. They would asphyxiate. Their sinuses could fill up with blood. They could drown in their own saliva. Honestly, I could talk for an hour about the ways that I thought these kids could die.

DAVIES: Terrible dilemma. You know, Chai, you got a lot of film about the authorities trying to weigh the risks in all of this. Tell us a little bit about some of those discussions.

VASARHELYI: Well, I mean, here was an impossible situation. Like, the water was - the rains could come any day, and they were running out of air. And there was really, like, no other option. And I think that what moves me in particular about this story was the absolute morality that Rick and Dr. Harris and John Volanthen, you know, demonstrate. You know, this was a terrible idea. They really thought that saving one child would be a success. And they were willing to take that risk for that reason. Like, one life was worth it.

And that - it just always kind of chokes me up because I have so much respect and admiration for that idea that if you're the only person in the world who can do something - like, is that your responsibility or not? And Rick, John and Dr. Harris rose to that challenge at great personal risk.

CHIN: I mean, they really had, you know, everything to lose, and they still chose to do it.

DAVIES: There was actually some concern. They were kind of informed that if they tried this - if the Thais permitted them to try this - and they did it and it didn't go well, they could face some serious consequences, couldn't they?

CHIN: Yeah. I mean, public opinion could turn. You know, it was being scrutinized by the entire global community, right? And so, you know, particularly if you're a doctor and anesthesiologist, if you're going to go ahead and do this and the kids die, you're going to be known as the anesthesiologist that killed these kids. You know, I mean, there's so many layers and levels of, you know, how much they had to lose. And yet they moved forward with this plan.

DAVIES: Well, some of them said there was - they'd been informed there was some concern that they might face arrest. There was actually a plan to get out of the country if they had to.

VASARHELYI: Which was a real - I mean, it's real. I mean, the Thai judicial system is severe.

DAVIES: The doctor, Richard Harris, who was also a cave diver, who would be the one to develop and I guess administer a lot of the sedatives to these guys and teach the other divers to do it, wanted to see the boys and make his own judgment about it. This is a part of the film from your interview with him in the documentary where he talks about swimming to the kids to see them.

(SOUNDBITE OF FILM, "THE RESCUE")

HARRIS: As I surface, the filth floating on the water meant we were in the final chamber where the kids were. When I realized I was actually about to meet these boys, of course, I thought about my own children. I was slightly horrified how thin they looked. And I could hear a couple of them coughing pretty wet coughs. They looked weak to me. But it is incredible to me, still - there was not one trembling lip, not a tear, not any sign of any concern. I just spent the whole time swimming and thinking about what we were going to do. And I guess that's when I decided that, yeah, I'm just going to have to get on board with this plan.

DAVIES: You know, one of the remarkable things about that clip is - and we've seen this in other observations - that the boys were enormously calm. They'd been there 10 days, initially without food. You managed to get them, you know, some food - not great food. But they didn't panic. Chai, how do we explain this?

VASARHELYI: You know, I think there are a few reasons. I think these are tough kids who grew up, you know, in a very rural part of Thailand, and they're used to hardship. For the most part, their parents are day laborers, and there's a lot of strength that comes from that. I think it's also cultural, where there is a certain stoicism that's part of, like, the Thai culture. And (unintelligible) I think they were totally depleted by this point. They almost had no more emotion to give. And then lastly, you know, they had their coach Ek with them, who did teach them how to meditate in order to just conserve energy and remain calm. And I think that had a profound, you know, effect on the children's ability to withstand the stress.

DAVIES: When the kids were in the cave before anyone found them, they were there 10 days without any fresh drinking water. I assume they had nothing to eat and ate the same water they peed and pooped in. Is that what they were facing?

VASARHELYI: Actually, the children had nothing to eat. That's true. However, they were able to drink the water from the cave itself. That was, like, the condensation, that which - it's essentially like filtered water because it's coming through a, you know, limestone mountain. So they had fresh water.

STANTON: When we first found them, although there was a language barrier, they expressed to us that, you know, when - they would get into the river and turn left as in downstream if they wanted to do any business, and they would turn right and go upstream if they wanted a drink. So, you know, there was plenty of water on tap. There was a massive flowing river at their feet filled with sediment. Sediment isn't going to do you any harm. I don't think - I don't believe it contained bacteria or viruses because of the remote nature of where it was.

DAVIES: It's remarkable. We need to take a break here. Let me reintroduce you. We are speaking with Chai Vasarhelyi and Jimmy Chin, a documentary filmmaking team who have made the new film "The Rescue," which is about an effort to rescue 12 young boys and their soccer coach who were trapped in an underground cave in northern Thailand in 2018. Also with us is Rick Stanton, a veteran cave driver who participated in the effort. We'll be back to talk more in a moment. This is FRESH AIR.

(SOUNDBITE OF DAN AUERBACH SONG, "HEARTBROKEN, IN DISREPAIR")

DAVIES: This is FRESH AIR. We're speaking with documentary filmmakers Chai Vasarhelyi and Jimmy Chin. They directed the documentary "The Rescue" about the effort to rescue 12 young boys and their soccer coach who were trapped in an underground cave in northern Thailand. Also with us - Rick Stanton, a veteran cave diver from England who played a critical role in the rescue effort since much of the cave was underwater. It was the water that trapped the boys and prevented them from getting out.

So after considering all of the options, all of them bad, they choose that - they decide they are going to try and get divers in, sedate the kids and guide them out. Rick, do you want to just describe a bit about some of the details here, how you were actually going to do this, what the kids would put on, how you would administer the sedatives?

STANTON: We put our heads together to come up with how we were going to transport them, the nuts and bolts, put them in a wetsuit. The crucial thing was the seal of their - obviously their mouth and the nose against the water. So we elected to have full face masks on them that actually maintained an internal pressure. So any leak would be outwards rather than water inwards because - I talked earlier about, you know, cave diving is all about redundancy. There was no redundancy in this case for an unconscious person with their face in the water. So that integrity of that mask seal was the most important factor.

Unlike most scuba divers that have the cylinders on the back, we elected to have the cylinders on the front. And that acted as a keel. It weighted them and kept them face down, which helped maintain their airway and made sure that no water would be aspirated upwards into the throat. But the most crucial part - Dr. Richard Harris did administer the first set of sedatives on the boys, but it was a two-and-a-half-hour journey out at least, maybe three in cases. And the sedative only lasted about 40 minutes. So we were trained - I say trained. We had a five-minute instruction on how to inject the boys, assess their depth of sedation and inject them with more sedative. And so that was part of the crucial plan that was put onto us. As we were driving out, we would have to perform this procedure.

DAVIES: So you put the kid in the wetsuit. You get the very tight mask. You or Dr. Harris injects the first sedative, and off you go. Can you just describe what it's like to maneuver the kid through these very tight spaces? Again, you can't see where you're going. You can't see your hand in front of your face, right?

STANTON: So all the four British divers that did this - they used to dive in through caves with unusual packages. Normally, it's a big tube full of our camping gear and extra equipment for some of our long explorations. And as we were putting this plan together, that's what we assumed we were doing. These were just inert packages. But of course, the moment you set off with this child, you realize that wasn't an inert package. This was a human life in your hand, and it was a breathing, living thing. And that really brought home the seriousness of it and the mission we were doing.

DAVIES: Were there places where you had to maneuver through a spot so tight that you would push the child ahead of you and then follow him?

STANTON: I describe it as a sort of letterbox that you had to post the child through. You couldn't see where the slot was, and you had to post the child through it by basically using the child as a feeler gauge to find where the appropriate bit was and then follow through behind. And, of course, all the time, you can't actually see their face unless you go really close to them. You don't know what's going on with that all-important face-mouth seal. Sometimes you couldn't even hear their breathing, so you had to sometimes just stop and take a reality check to see that they were actually still alive.

DAVIES: Jimmy, you want to describe what the finish line was like - that is to say, when one of the divers brought one of the kids to the point at which they could be taken care of by other rescue workers? Just describe that scene for us, what happened once the kid got out of the water.

CHIN: Well, this operation was massive - right? - because, you know, even once they got the children to Chamber 3, there was still, you know, a huge amount of cave left to move the children out. And so there were hundreds of volunteers and Thai navy SEALs, American Special Force PJs all transporting them out through this, you know, kind of treacherous terrain. It's just really hard to describe the scale of it, you know? And I would imagine for the divers, you know, who are really, really focused on this task, once they handed the child off, all of a sudden, you know, all of those emotions that have been set aside would probably rush back in.

DAVIES: Yeah. Rick Stanton, what did it feel like when you got one of the children to the end and could see that he was still alive?

STANTON: Yeah, that was amazing. I mean, the relief was enormous. And on the first - I was the last one. And of course, of that day, last one of those four. I had no idea what had happened, preceded me, whether anyone got out alive. So you know, to be told that the previous three had all survived - and obviously, I knew my one was alive - that was just an amazing relief. But of course, you have to remember, that didn't mean to say - just one day of success didn't mean to say the next day or the day after was going to be an equal success. The probability of something going wrong was enormous, and so there was absolutely no room for complacency in this rescue.

DAVIES: You know, and as if someone were writing this for a TV script, after the first two days, you had one day to go. And then the skies opened, and the rains got really intense. Chai, describe what effect that had on everybody.

VASARHELYI: Yes. And after the second day of the rescue, you know, the monsoons hit like with full ferocity. I think they described as monsoons on steroids. And it was, again, that ticking clock. The caves would flood, and there was really - either take the chance right now on the third day of the rescue and try to get the kids out, or you may not have a chance again. And again, like, that idea that, you know, Rick, John and all the cave divers were willing to do that - to go ahead and put themselves in that position in order to save these children they've never met before. Kind of gets to the heart of this story, right? It's about, like, being your best self, doing the right thing that - you know, I don't - again, always makes me quite emotional when I think about it.

DAVIES: When you have a skill that no one else has and you've got to decide what you're going to do with it in that moment. You know, the scene of when one of the kids arrives from the water - one of the divers guides it through. And then there's these amazing shots of this huge chamber that is filled with hundreds of workers. And there - the kids are simply passed up, you know, from hand to hand to hand. This is amazing footage. Chai, where did you get that stuff? I mean, you weren't there at the time. You had to go back and try and track this down. Where did all this amazing footage come from?

VASARHELYI: We'd been told by Rick and John that they were given GoPros by the Thai navy SEALs, but no one had seen the images. So it became - like, kind of it triggered this, like, two-year quest to collaborate with the Thai navy SEALs to try to get access to their footage and also to include their point of view in the story because they clearly played a very important role as well. And you know, there's some things that can be achieved in a pandemic, and there's some things that can't. And trying to forge this relationship and build trust over Zoom really didn't work. So it was when I got my second vaccine, I got on a plane to Thailand. And, you know, we re-approached the Thai navy SEALs again and again. And they finally said yes. And what we were - we were anticipating maybe 90 minutes, you know, maybe a few usable shots. They had 87 hours of footage, and it was extraordinary. It's kind of like the best type of nonfiction story. Like, you would - it was stuff we'd dreamed of finding. We couldn't even imagine that it existed, like those shots where you see the 200 people passing the boys on a stretcher up through the cave or the shots of when you actually see John and Rick emerge from the cave, having discovered the boys and letting the Thai navy SEALs know. You know, all of this stuff has never been seen before in the world, and we felt - it just was one of those again, like, fortunate events or good fortune that surrounds this story where we were able to find that footage at the very last minute and get it into the movie.

DAVIES: Let me reintroduce you again. We're going to take another break here. We're speaking with Chai Vasarhelyi and Jimmy Chin. They directed the documentary "The Rescue," which is in theaters now. Also with us - Rick Stanton, a veteran cave diver who played a critical role in that rescue effort in Thailand. We'll talk more after this short break. This is FRESH AIR.

(SOUNDBITE OF PETE YORN'S "ON YOUR SIDE")

DAVIES: This is FRESH AIR. We're speaking with documentary filmmakers Jimmy Chin and Chai Vasarhelyi. They directed the new documentary "The Rescue" about the efforts to find and save 12 young boys and their soccer coach who were trapped in an underground cave in northern Thailand in 2018 after heavy rains blocked their escape routes. Also with us is Rick Stanton, a civilian cave diver from England who played a critical role in the effort. The film of the 18-day drama, titled "The Rescue," is in select theaters now and will open more widely on Friday.

Well, you know, Rick, I mean, this is - you've been cave diving for a long, long time. I mean, what motivates someone to do this kind of high adventure is always a little mysterious to me. But this is a case where you were summoned. And you had a entirely unique skill, which was needed. And this involved a lot of risk. Did you feel morally obliged to do this? Did it change the way you look at cave diving?

STANTON: From the moment we found the boys, John and myself, we did, of course, have a moral responsibility. Of out all the 5,000 people that were there, we were uniquely placed to understand the situation and to put forward the rescue. So that was a huge responsibility. And from that moment when I came out of the cave, having found them, I completely changed. And all my efforts were directed towards the rescue and to saving those boys.

DAVIES: And did it change you, you know, in the weeks, months since?

STANTON: I would say that we were very confident people before the rescue. We wouldn't have been there putting forward such an audacious plan if we weren't confident in ourselves and our techniques and our decisions. But this is - as you say, this is a very strange hobby, which we've really pursued for 40 years just for our own perverse enjoyment and pleasure. And what really brought it home to me is, suddenly, it all became worthwhile. And then this obscure sideline hobby that no one could understand or vocalize all came good and was of huge benefit to those 13 young lives and done on a world stage. So I'm hugely proud of that event and the fact that my life almost, you could say, led to that point. All decisions that I had made led towards that one circumstance.

DAVIES: Have you stayed in touch with the families at all?

STANTON: Not really because of the language barrier. But I do get pictures sent to me of the boys, like, when they graduate from school. I sometimes see pictures of that. You might be amazed to hear that they still go in the cave.

DAVIES: (Laughter).

STANTON: So four of those boys went on a trip with Vern and my girlfriend at the time only a month or so ago went on a 24-hour-long trip in there. So it hasn't particularly traumatized them after the event.

DAVIES: You know, people who climb Mount Everest or other peaks get amazing views and experiences that nobody else will get. What's the corresponding thrill that you get from exploring a cave? What's rewarding about it?

STANTON: The simplest way to describe that - the surface of the planet is being photographed. Not every place has been reached. Not every peak has been scaled. But in a cave, you've no idea what's going to be around the next corner if you're the first person there. And it's an opportunity to literally explore where no man has been before. And it doesn't require the - you know, going to the deepest ocean or the most remote part of the world and then climbing a mountain. You know, we've explored - we've had the privilege to explore caves. In our own tiny, overcrowded island, you can still find places, many places and significant places from a caving's perspective where you're able to explore. And that's - for me and for us and for the U.K. team, that's the essence of why we do it. It's - we're fascinated by caves or say we're cavers not necessarily - we just use the diving equipment to extend out what we want to do. It's that essence of discovery and finding out what's there.

DAVIES: So you're repeatedly the first human being to see certain things (laughter).

STANTON: That's correct.

DAVIES: Well, Rick Stanton, Chai Vasarhelyi, Jimmy Chin, thank you all so much for speaking with us.

CHIN: Thank you so much for having us.

VASARHELYI: Thank you.

STANTON: Thank you.

DAVIES: Chai Vasarhelyi and Jimmy Chin directed the documentary "The Rescue." Also joining us was Rick Stanton, a veteran cave diver who played a critical role in the rescue effort in Thailand. "The Rescue" is in select theaters now and will open more widely this Friday. On tomorrow's show, Amir Questlove Thompson, co-founder of The Roots, musical director for "The Tonight Show" and director of the documentary "Summer Of Soul," returns to our show. He'll talk with Terry about his new book, "Music Is History," in which he chooses songs from each year since his birth that connect with memorable parts of his life and recent history. I hope you can join us.

(SOUNDBITE OF SONG)

UNIDENTIFIED MUSICAL ARTIST: One, two, three.

DAVIES: FRESH AIR's executive producer is Danny Miller. Our senior producer today is Roberta Shorrock. Our technical director and engineer is Audrey Bentham, with additional engineering today from Al Banks and Adam Staniszewski. Our interviews and reviews are produced and edited by Amy Salit, Phyllis Myers, Sam Briger, Lauren Krenzel, Heidi Saman, Ann Marie Baldonado, Thea Chaloner, Seth Kelley and Kayla Lattimore. Our digital media producer is Molly Seavy-Nesper. Therese Madden directed today's show. For Terry Gross, I'm Dave Davies.

(SOUNDBITE OF SONG)

UNIDENTIFIED MUSICAL ARTIST: Agrisolo (ph).

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