When Richard Harris pushed an unconscious Thai boy underwater in a bid to save his life, it went against every instinct he had as a doctor.
"I could think of a hundred ways that this could fail and I could not think of a single possible way that it could succeed," the South Australian anaesthetist and expert cave diver said as he recounted the extraordinary rescue of 12 young boys and their coach from a flooded cave in Thailand.
"To push the kid's face into the water... I can't tell you how wrong that feels to push an unconscious person's face into the water."
Speaking at a diving conference in Sydney, Dr Harris told of his fears for the children and resistance to the "madness" of sedating them - until it became clear there was no other option.
He comforted himself with the knowledge they would at least drown while asleep if anything went wrong.
"In a way, that was the only way I could actually justify it in the end," he said on Saturday night.
Dr Harris administered the drug ketamine to each of the boys to stop them from panicking while they were rescued.
He also gave an "anaesthesiology 101" lesson to other divers who would need to top up the boys with further drugs when the initial dose wore off during the rescue mission, which would take hours, he said.
Dr Harris and his dive partner, retired Perth vet Craig Challen, were among an international team of cave-diving experts who managed to free the Wild Boars soccer boys and their coach in July last year.
The veteran cave divers drew worldwide praise and admiration for their part in the dramatic mission, which captured headlines around the world.
The pair were named joint 2019 Australians of the Year in January.
When asked by an audience member about the award, Mr Challen said he was still getting used to being bestowed with honours.
"I've been accused of maybe a bit of false humility but I honestly do believe that we just did what anybody would have done," he said.
"We were fortunate that we had this peculiar set of skills and experience that we could bring to bear."
The divers said they missed going on adventures because of a busy schedule for the year, but they wanted to make the most of the opportunities presented to them.
"Sadly, our cave-diving program has been significantly curtailed," Mr Challen said to laughter from the audience.
"But I do believe the caves will still be there in another year, so we'll make the most of it.
"It's clearly a high point in our lives."