Hero British diver tells of mission to rescue last two Thai boys

The divers used a three-inch-thick guide rope they pulled themselves along against the current with one arm while dragging the boys with the other. Photo / Supplied

After three treacherous days, the massive rescue effort to free a boys football team from a flooded cave in Thailand was almost over.

Only one of the 12 boys remained trapped and British rescue diver Jason Mallinson was readying him to escape through the murky tunnels.

Time was running out as conditions inside the Tham Luang cave deteriorated and divers could barely see their hands in front of their face, reports Daily Mail.

However, when he tried to fit a breathing mask around the young boy's face he discovered to his horror that it was too small.

"We put it on him, really strapped down tight so his nose was flattened against his face and there was a big gap under his chin. We just couldn't get it to seal," he told ABC's 20/20.

Mallinson feared the boy would drown and there was no way to contact rescuers outside the cave to bring in a new mask and no time anyway.

Australian diver and anesthesiologist Richard Harris had also already dosed the boy with ketamine to keep him calm and still during the perilous dive.

The pair tried a different mask they hoped would seal properly and stop the rescue becoming a disaster at the last hurdle.

"We knew we didn't have any more time and we knew this was the last option," Mallinson said.

Divers from the rescue mission, from left to right: Chris Jewell, Mike Clayton, Rick Stanton, Lance-corporal Connor Rae, Josh Bratchley, Gary Mitchell and Jim Way. Photo / Supplied

"Once you set off with that kid, it was a one-way journey. You weren't going back to where they started … It was a case of getting him out. A bit brutal but dead or alive."

The hero diver said he was nervous guiding the boy through the tunnels because the replacement mask could easily come off sideways if it was bumped.

Visibility in the tunnels was almost zero and the rescuers couldn't see the boy as they pulled him along, so Mallison used his own body as a shield.

"I developed a technique where I'd pull him in really tight with his head just down here," he said, demonstrating.

"And, I'd extend my head over the top of his so my head hit the wall first and it so protected his head."

Mallison said he hit his head dozens of times on the cave wall but had to keep up the pace so the child didn't develop hypothermia.

Meanwhile, fellow British diver Chris Jewell was having his own problems guiding the second last boy through the cave ahead of them.

The boys had held out in chamber 9 and needed to reach chamber 3 where other rescuers would help them over the caverns that weren't flooded.

The divers used a three-inch-thick guide rope they pulled themselves along against the current with one arm while dragging the boys with the other.

The rescued soccer team members pose with a sketch of the Thai Navy SEAL diver who died while trying to rescue them. Photo / AP

In chamber 4, Jewell lost his grip on the rope and was completely lost in the darkness and unable to feel out the rope with his flailing arm.

Instead he found and electrical cable he hoped would lead him forward, but actually sent him back towards the end of the cave.

Disoriented and realising he wasn't going the right way, Jewell decided to surface and get his bearings, putting the boy on a rock outcrop.

"I surfaced in a different section of the cave and I really didn't know where I was for several minutes," he told 20/20.

Eventually, Mallison and Harris caught up with him and the doctor was able to take over while Jewell followed behind.

"I followed him closely behind just making sure that he didn't have any problems in the way," he said.

Finally they all reached the mouth of the cave and the rescue was over with every boy safely recovered from their murky tomb.

Despite risking their lives multiple times to save complete strangers, the pair sand they don't feel like heroes, just people with skills that could help.

"I don't feel like a hero. I just feel like someone who was in the right place at the right time with the right skills to make a difference," Jewell said.