Transcript for Divers describe the daring plan implemented to rescue boys from Thailand cave

Hey folks I'm back up and ABC news here in Hong Kong and we're bringing to you tonight on 20/20 this incredible story so. It shatters everything that anybody thought they knew about the rescue at the cave earlier this month. And of what we lowered in producing it is first of all that. Nobody really thought that this mission could succeed so there is a meeting Friday night before the Sunday rescue and at this point the Thai government wanted a zero risk option. And it was believed that the zero risk option which is to wait out the monsoons until November. Let the kids syndicate try to get enough food in their in the air for them and that way it'll survive an industry able to walk out. But the American planners who did sort of surveying everything and a British divers who were really the best in the world. And the Australian doctor was we're going to be taking care of them and basically the anesthesiologist. Longs and Thai Navy SEALs came to the government and say listen. You keep them in their. Even for a couple of weeks and are gonna die. The oxygen level is at 15%. We can't get enough food in there for then and the Thai Navy SEALs were staying with them. They're gonna die the only way out is diving them out and that was a perilous journey and they told the government that night. We have to do this now we have to do it within the next 48 hours before the monsoon comes or the going to die but even if we do dived and out. There is a significant risk that. 34. Even six of them might die as there extracted from the cave the Thai Navy SEALs believe that. At least 50% of the thirteenth. Boys and soccer coach would die and you know they were willing to tolerate that for them that would've been a success even if one person had come out alive to his parents so. When it actually happened they got everybody out alive nobody believed it was possible but. There was some really really touching go moments and in the beginning the first dive out they had to date of the boy completely using Kevin mean. Which is basically a clinical anesthetic. Kids out cold Jason malice in the diver the British divers swimming with him through the cave swimming with him holding him and carry him through as he's swimming. Indicate starts coming to. Jason Allison doesn't know what to do could she's never actually ministers shop before he's not a doctor. He decides he's got he's got a couple of syringes he paints him up against the wall he finds this a range there. Medecins and things floating around in the water around him. Finds the kids die. Gives them the shot. He said dated may continue and he's got to do it three more times before the end of that single journey. Another diver another parade. Got lost on the way out he let go of the guide rope by accident because. The guys consistently had to shift the boys from hand to hand depending on the obstacles in the water sometimes they were swimming through areas that were you know barely two feet high. So he's doing this loses the guide rope and is it going the wrong way in getting hopelessly lost in the cave luckily a couple of the other divers were coming through. I help them steer in the right direction and he got out and it's stories like these that we put together tonight's 20/20. That completely up and everything we thought we knew. About how this rescue operation happened also. Those brits and aussies they got immunity because they were so convinced that people were going to die on the way out. That they needed to protect themselves as well against liability so they got diplomatic immunity. And somehow. They got all of those kids out alive together. And now they're at a monastery in Thailand basically doing. Good deeds in community services and charity work to give thanks and basically to pay homage to. The X and Thai navy seal some on going on who lost his life. Preparing for the rescue a staging air tanks and down the a lot of people still thinking about the life that was lost but also. Very very happy that they were able to save so many lives. Cell I hope I stay tuned watch tonight 20/20. 10 PM eastern time. And probably nine AR Campion and other places depending where you are. But stay tuned watch it it's going to be an incredible hour again back up and here ABC news in Hong Kong see you soon.

This transcript has been automatically generated and may not be 100% accurate.