An Australian doctor and cave diving expert has played a critical role in the precarious mission to save a young Thai soccer team from their prison cave.
Adelaide anaesthetist Richard Harris, who has 30 years of diving experience and has led cave rescue and recovery missions before, risked his own life on Saturday to make the treacherous journey to the chamber where the boys have been trapped for 15 days.
It was on his advice that the first four boys were cleared to make the incredibly dangerous journey out of the flooded cave complex, emerging alive on Sunday.
Foreign Affairs Minister Julie Bishop says the doctor's expertise is in high demand as the rescue mission rolls on, with the aid of 19 Australians.
"He has a diving support partner with him as well. The Australian doctor was in the cave - he was part of the medical assessment to determine that the boys were fit enough to dive and swim to freedom," she said on Monday.
Dr Harris continues to play a key role in the ongoing international effort to get the remaining eight boys and their coach to safety.
Rescue divers and the boys must dive, swim and climb their way to safety along a pitch-black tunnel that at points is barely big enough to allow an adult human body to wriggle through.
Those who know Dr Harris say his unique set of skills to give the ongoing rescue the best chance of success.
David Strike has known Dr Harris for more than 10 years, and says his medical expertise and experience as a cave diver and retrieval expert is invaluable.
"Richard is just one member of a team of uniquely qualified and extraordinary people prepared to sacrifice their own comfort, safety and well-being for the benefit of others. It's an over-used term, but all of those involved are true heroes," he told Fairfax media.
Dr Harris has spent the past six years working for MedSTAR, an aeromedical retrieval service for the South Australian ambulance service.
His exploration and photography has gained him a following in the international cave diving community.
He is a leading expert in cave rescue expertise in Australia, and in 2011, had the difficult task of recovering the body of his friend, cave diver Agnes Milowka, after she ran out of air in Tank Cave at Millicent, near Mount Gambier.
After that operation, he spoke of seeing his friend's body submerged in about 20 metres of water, half a kilometre from the mouth of the cave. She had run out of air after becoming separated from her dive buddy and could not find her way out.
"It looks like she has remained very calm right to the very last breath while she has been working to extricate herself," Dr Harris told The Australian at the time.