Peter Faulding, founder of rescue response provider Specialist Group International, said the right team of people were handling the operation but warned of the dangers faced by the divers and the children.
He said air supply for everyone involved would be one of the biggest issues to deal with given the length of the journey in and out of the cave. He predicted it would take four hours to get in and four hours to get out.
The only way to get to the group is by navigating 2.5 miles (4km) of dark and tight passageways filled with muddy water and strong currents, as well as oxygen-depleted air.
Mr Faulding told Sky News: “Besides the claustrophobia, it’s full of water and silt and they have got to keep their nerve.
“I would imagine there will be two divers bringing each child out.
“One of the biggest issues for the children is oxygen deficiency and CO2 build up is an issue too. It causes fatigue and all kinds of issues.”
“The children may have to exchange mouth pieces and the divers will be following a line in – they’re not free swimming it – and that will be laid into the passages,” he added.
Thirteen foreign divers, five Thai divers and five Navy SEALs are taking part in the complex operation, with the boys expected to gradually exit the cave.
Four boys from the group, which has been trapped for more than two weeks, have been freed so far after officials previously said the mission could take up to four days.
Mr Faulding said the children could be taken out on rescue sleds or stretchers and have an air line running directly to them.
Rescue workers could also use through-water or hard-wire communication tools such as air masks with in-built two-way radios that would allow a child and a diver to speak while navigating through water in the cave.
Mr Faulding said the children’s inability to swim would not cause a problem as long as they could manoeuvre themselves and showed “confidence to be in the water”.
Former Navy SEAL diver Saman Gunan died while taking part in the rescue effort during an overnight mission in which he had been delivering oxygen canisters in the Tham Luang cave system.
“It’s a highly dangerous operation – I can’t stress that enough. If it goes wrong there’s no way out. If they run out of air you have got a big problem, it’s very, very dangerous – there’s no second option really,” said Mr Faulding.
“There’s no one to come to the rescue and bring you out. Because it’s inside a big mountain, they can’t build a shaft down to rescue them, it’s solid rock above them.”
He added: “It’s a major feat of physical endurance just to get the [air] cylinders through. The physical side will have a heavy effect on the rescuers – they have got to be very fit to do this.”
Mr Faulding said the operation could go down as “one of the greatest rescues in history” and compared it to the rescue of the 33 Chilean miners in 2010, whom he said did not have the issue of water to contend with.
He added: “This is a very high risk operation.”