An expert cave diver based in Co Clare who helped in the heroic rescue of 12 Thai boys and their football coach has described the conditions and visibility inside the cave, saying “it couldn’t get any worse”.

Jim Warny, who is originally from Belgium but lives in Ennis, returned from the rescue mission on Friday to a hero’s welcome.

Mr Warny, who has been cave diving for 20 years, has opened up about the length of time it took to reach the boys inside the cave through flooded sections from five metres to 350 metres long.

In his first in-depth interview, which airs on RTE Radio 1 on Tuesday, the father of one described the intricate rescue mission that gripped the world.

After he was asked by the British Cave Rescue Council to help the Thai navy Seal divers, Mr Warny was on a plane within a few hours.

Speaking to presenter Philip Boucher Hayes, he said: “It was always in the back of my head that I would get the call – I happened to see that one of the guys out there was active on Facebook and I text saying, ‘I’m here if you need me’ and he replied instantly saying, ‘How quick can you be’?

“I said two hours, and then five minutes later I was packing my bags to go and flew out the following morning.”

After arriving at the Tham Luang caves, Mr Warny saw first-hand how difficult and complex the conditions were.

“Visibility couldn’t get any worse, it was zero visibility,” he said.

“I wasn’t out of my comfort zone, it was more the psychological part of being responsible for a human life.

“The initial part where most of the military personnel and non-diving were based was about a kilometre in, mostly walking, wading and one short section that was initially flooded that they had pumped out.

“You would have to wade through, just enough to keep your head above the water.

“Then the cave diving starts and it’s varied between fully flooded sections – the shortest part was five metres long and the longest was 350 metres long.

“It was a mix of flooded sections and sections where you would swim on the surface.

“There was one section where we had to get completely out of the water and put the boys on a stretcher and try to carry them for 200 metres.”

With little time to prepare the young boys, a number of the divers carried out tests with schoolchildren in a local pool to determine which mask to use.

One of the biggest issues facing the divers and the boys was managing their stress, as “you can’t panic under water”.

He continued: “So we came to the conclusion there had to be some level of sedation.

“They were close to being fully sedated – if anything went wrong it would have jeopardised the survival of the boys.”

Towards the end of the rescue mission, Mr Warny was asked by a lead diver to assist and he helped bring one of the boys out of the cave.

“It was a miracle everything worked, there were difficulties, yes, but there was an amazing team involved,” he added.

As they edged close to the end of the mission, water started to rise inside the cave at an “incredible rate”.

Ten people were still inside the part of the cave that had a gap large enough to keep your head above water.

“That gap was closing quickly,” Mr Warny added.

The experienced team, however, made it out safely.