He was meant to be holidaying on South Australia's Nullarbor Plain, but instead, an Adelaide anaesthetist has been plunged into the spotlight, working among the international rescue team to extract a soccer team and its coach from a flooded cave in Thailand.

Richard "Harry" Harris was due to travel to the Nullarbor on Friday for a cave diving holiday but cancelled his plans at the last minute after receiving a call from expert divers from the UK on Thursday.

Thai authorities have said 90 divers are involved in the rescue, 50 of them foreign rescue workers.

Dr Harris' friend and colleague of more than 20 years Michael Eaton said the Adelaide doctor's expertise was matched by very few people in the world.

"He has just got so much experience of diving in so many different places around the world, I know for a fact he has dived in China on several occasions, once at the request of the Chinese government in fact and it's the same sort of geology across South East Asia, it will be sort of limestone cave networks," Dr Eaton said.

"I have been on many holidays with Harry — every trip with Harry is an adventure and when we go on a Harris holiday we call it a 'Harris Adventure Tour'.

"He is of course the main man on the Harris Adventure Tour and this is one sort of adventure."

Richard Harris has travelled around the world exploring and helping with challenging medical retrievals. ( Supplied: Michael Eaton )

Dr Eaton said it was a tribute to his friend's skill that the British, known as the best cave divers in the world, wanted the Australian medical specialist on the ground in Thailand to help with the rescue.

"It is a big honour and a big deal and it is really dangerous what they are doing because of course it's not just preparing in the usual sort of pristine clean water that they normally do, this is really hazardous I think," he said.

"There is no visibility, there is all of these currents, the demand of trying to get people out who can't swim.

"This is not the usual well-planned thing where you can make decisions sensibly and it would be a lot of pressure on them… we are looking forward to him coming home."

Dr Harris' colleagues at MedSTAR have been watching his contribution to the Thai cave rescue from their base in Adelaide. ( ABC News: Rebecca Puddy )

Things can go wrong quickly

Bill Griggs, Dr Harris' former boss at the South Australian Ambulance Service's MedSTAR emergency medical retrieval team, said attention to detail was important for cave divers as well as anaesthetists.

"To do cave diving, you have to be all about attention to detail and you have to be meticulous," Dr Griggs told ABC Radio Adelaide.

"Things can go wrong very quickly if you don't have your back-up plan, [and] Harry also brings that to his practice of medicine."

Dr Harris completed his medical degree at Flinders University in Adelaide, before undertaking a postgraduate certification in aeromedical retrieval through James Cook University.

He took over as MedSTAR's head of retrieval co-ordination when Bill Griggs left the position in 2016.

Dr Harris has extensive cave-diving experience spanning several decades, and has completed complex dives all over the world, including in China, Christmas Island and New Zealand.

Dr Griggs, who was involved in the medical response to the Bali bombings, said it was Dr Harris's "fairly unique" combination of medical knowledge and cave diving that led to him being asked to join the Thailand mission.

"He has done many things with the cave diving over many years and he is known to a very small group of people who have that very high level of expertise," Dr Griggs said.

"The combination of his medical knowledge and his cave diving skills was clearly [why] the British guys requested that he come as well."

Dr Harris is "all about attention to detail", Dr Griggs says. ( Facebook: Richard Harris )

Dr Harris a 'selfless', 'extremely thoughtful' person

MedSTAR clinical director Andrew Pearce said he was staying in touch with Dr Harris to check on his welfare while he was at the rescue site.

Dr Harris was part of the Australian medical assistance team registered with the Department of Foreign Affairs and Trade.

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"He's not someone you just stumble upon overnight — it takes years and he's got over 30 years of diving experience," Dr Pearce said.

"He has the right skill mix and he's the right person."

Dr Pearce described the Adelaide-based anaesthetist as selfless, extremely thoughtful and a quiet person who had previously avoided media attention.

It is understood that Dr Harris had previously participated in several difficult retrievals, including the recovery of the body of his friend, Melbourne diver Agnes Milowka, from Tank Cave near Mount Gambier in 2011.

In 2015, Dr Harris was presented with an outstanding achievement award at OzTek's Advanced Diving Conference and Exhibition.

According to his profile on the Specialist Anaesthetic Services website, Dr Harris "has managed to combine his taste for adventure with his medical practice and a lifelong interest in the underwater world".

"His love of underwater exploration has led him to work on National Geographic documentaries, feature films and with various teams worldwide in the role of diver, underwater cameraman and of course medical support.

"This led him into the field of diving and hyperbaric medicine. His work at South Australia's emergency medical retrieval service (MedSTAR) as an aeromedical consultant continues to challenge him with the care of critically ill patients in remote and austere environments.

"He is a member of the Explorers Club of New York and recently received an Australian award for 'Outstanding Contributions to Cave Exploration'."