Transcript for ABC News' Matt Gutman speaks out about his new book 'The Boys in the Cave'

We'll switch gears to that miracle rescue from a cave in Thailand, 12 boys and their coach surviving ten perilous days trapped in darkness before they were rescued and Gutman was there on the scene and wrote a book about it called "The boys in the cave," Matt, as a parent, this touched you deeply. I was on vacation with my kids and like so many other people, the story resonated because my daughter is 10 years ole. She plays on a soccer team and go on excursions and the thought of her and her team being lost in a cave was horrifying. As soon as I heard they were discovered I had to get to Thailand and luckily we work for a fantastic company and through their resources it became the feel-good story of the year because they got out. Amazing. The whole world watching. Why was it so perilous trying to get them out? Everything was stacked against them. The morning going into the rescue itself after the kids had been in there for 16 day, the divers themselves who were bringing them out thought that maybe 75% to 80% of the boys would die. That's up to 10 of the boys of the 12 boys in the cave plus their coach. Everything was against them. They had been in there for 16 days with no food. No oxygen, the oxygen had been down to 15%. 30% less than you and I are breathing right now. No light, no families. They heard chickens and humans and dogs barking and then the divers basically had to drug them and drag them out through one of the most complicated cave dives in the world. I know I was asking and a lot are asking why did they have to sedate them. The kid was have panicked in this murky water. The dive is endless. It took three hours and so the concern was that if they woke up and panicked or if they were swimming and panicked, they could hurt the divers, possibly killing both of them at the same time. So the prerequisite for the divers to go through with this was that the boys had to be sedated and they were so knocked out, Lara, you could have done open heart surgery, amputated a limb. The problem is every 20 minutes they had to resedate them because they were using ketamine so they had to find an opening where they could get out of the water and resedate the kids and these are like British cave divers. They've never injected anyone with anything and here they are in the dark tunnel trying to sedate the kids and they had to do it four times. Everything that could go wrong. I'm going to get a little active but you're talking about areas that are -- the distance from the chair to the floor and they're stuffing the kids through that space in this dark for over a mile and, you know, it's just krerd they made it out. You're so connected to the story and you've actually gone back, checked in with the families. How are those boys doing now. They're doing well and one thing that surprised me about the parents, here, right, your natural inclination if your kids survive something like this, you hold on so tight but in order to hold on they had to let them go and allow them to be adventurers.d one of the boy's birthday parties riding around on dark on mopeds. Life goes on in a beautiful way. I know you're so passionate

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