PERTH hero diver Craig Challen has spoken exclusively about the Thai cave rescue and why he feared not all the boys would get out alive.

The retired vet and cave-diving expert yesterday revealed details of the unprecedented rescue that gripped the world this week.

With the 12 Wild Boars and their coach safe in hospital after their miraculous three-day extraction, Mr Challen returned home still in disbelief over the success of the operation.

Speaking exclusively with The Sunday Times he revealed:

· When he first arrived in Thailand he thought the mission would be a recovery rather than a rescue;

· He didn’t think the boys and their coach could survive underground for months;

· He and Adelaide anaesthetist Richard Harris instructed the Wild Boars themselves to collectively decide who would be extracted on each day of the operation;

· Each of the boys was medicated before they were extracted to the extent “they didn’t know what was going on”; and

· The narrowest section of the cave – reportedly 38cm in width – required divers to attach an oxygen cylinder and mask to each boy before guiding them through on a tether.

Mr Challen said when he and Dr Harris arrived at the cave the pair thought “we were there to do recoveries, so the actual outcome was unbelievably good”.

“It wasn’t dangerous for us but I can’t emphasise enough how dangerous it was for the kids,” Mr Challen said.

“It was absolutely life and death. We didn’t expect to be getting 13 people out of there alive.”

By the time he and Mr Harris reached Tham Luang on Thursday July 5 – three days after British divers first discovered the soccer team perched on a tiny sandy ledge – Mr Challen said the outlines of the eventual rescue plan were already in place.

“Everybody was just frantically trying to work out what the best away to go about it was,” he said.

“(Richard and I) developed the plan a little bit, changed some of the equipment and stuff like that but it was really the British divers plan – they really deserve the credit for the extraction plan.”

At the time, pumps working around the clock in moderate rain were struggling to dent water levels in the 2km long labyrinth.

And with heavier showers predicted, Mr Challen said the extraction team had no choice but to spring into action.

“It is the start of monsoon season there and once that happens properly the cave completely floods and it would become undivable,” he said.

“There was some talk that if they couldn’t be extracted by us they could be supported for the three or four months until the water levels dropped again.

“Our judgement was that was impossible, that once the cave became undivable you wouldn’t be able to get supplies in to them on any sort of regular basis.

“We didn’t think they would survive all that time underground, they would start getting infections and sick and we didn’t think it was an option.

“With the rain coming we knew that we had to go in, in our judgement it was pretty urgent.”

A highly experienced cave diver, the 53-year-old said getting in and out of the system alone was not particularly difficult.

“As far as the site goes, cave diving is what we do so the dive wasn’t in and of itself that bad,” he said.

“But, that fact that you have got a living, breathing little tiny person that you are in charge of and you are very limited as to what you can do to help them, and it is a two hour journey out of the cave… it was taxing.

“We had practiced and trained for rescues but nobody has ever conceived of anything like this at all.”

Mr Challen said the age, language barrier and lack of swimming ability among the boys meant the Thailand extraction was far more difficult than its only real comparison, the Alpazat cave rescue in Mexico where six British soldiers were successfully rescued after being trapped underground for six days.

“That was an order of magnitude less difficult in the sense that the people being rescued were military guys, English-speaking, they could handle themselves and be taught to dive and (British diver Rick Stanton, who also played a pivotal role in Tham Luang) basically just dived them out of the cave.

“There wasn’t the same distance involved as in this case either.

“This is a first, and hopefully last. I hope my career is well and truly over by the time the next one happens.”

Beginning Sunday, July 8 on each day of the rescue Mr Challen would accompany Mr Harris to the boys, where those being extracted were medicated.

“They had drugs,” he said.

“We could not have panicking kids in there, they would have killed themselves and possibly killed the rescuer as well.”

Mr Challen’s role at that point was to help the boys through the section of the cave system nearest the platform they were found on.

“There was short dive until a dry section and then they had to be de-kitted, helped about 200m over rocks and sand hills and stuff and then (kitted back up) and put into the water again,” he said.

“I was responsible for running that operation with two other guys.

“I stayed there until the last boy each day. They would come through at 45 minute intervals, because that is how long it took for that transfer.

“We would go one, two, three four and then everybody swam out after the last one.”

One of the trickiest parts of the rescue was manoeuvring the kids underwater through the narrowest section of the cave.

“You couldn’t fit a stretcher through and it was one diver only per patient,” Mr Challen said.

“The kids had a vest on and the cylinder attached to them in front. They were wearing full face masks and then a tether to the diver.

“There was no point having two divers because you are single file anyway and it is only 10cm visibility in front of you so you couldn’t see the other diver anyway.”

As the rescue process became more streamlined the divers were able to reduce the total time it took to get a child from the ledge to safety from three hours to just over two, allowing them to remove the remaining four boys plus their coach on the third day.

Prior to heading home, Mr Challen said he had been able to check up on the team and their coach as they recovered in Chiang Rai in northern Thailand

“We were able to visit the boys in hospital on Wednesday afternoon, which was immensely rewarding,” he said.

“There has been some talk of a visit in the future but I think for now they just need to go home to their families and get back to normal life.”

Sadly, the rescue was not without tragedy after former Thai Navy Seal Saman Gunan died while resupplying the cave route with oxygen tanks just before Mr Challen arrived.

“Although it was a big shock, everyone was focused on the objective of the rescue and there was no lessening of our resolve to get the job done,” he said.

“The time for reflection on these things is later.”

Now back home, the decompression process has just begun for Mr Challen, who said he planned to escape Perth for a few days while the media frenzy died down.

On one point though, he is already adamant – no further recognition is necessary.

“We were lucky enough to be available and have some skills that we could offer that contributed towards the great outcome,” he said.

“There were hundreds of other people there that worked just as hard as us and won’t get any awards. The fact that all the boys are out of the cave and healthy is reward enough.”