A world renowned cave explorer says getting all 13 people out of a cave network in Thailand is tricky, but not impossible.
All 12 members of a Thai youth football team and their coach who went missing in a cave network in the north of the country were yesterday found alive, nine days after they disappeared, 4km from the mouth of the cave.
Rescuers are now weighing up the options for retrieval. They will either be accompanied out with dive gear, or wait until water levels drop so they can walk out.
World Caving Association honorary president Andy Eavis told Nine to Noon he was optimistic they would get out, but survival rested on them remaining mentally alert.
The next 24 hours would give rescuers a clearer picture of group and their condition, he said.
"That, I think, will dictate the next stage - whether people really go for it to get them out.
"There are options on diving them out which are relatively safe, but I don't think you could say it's 'zero risk'. I think that's probably unrealistic," Mr Eavis said.
Mr Eavis is the former president of the British Caving Association and knows the two British divers, John Volanthen and Rick Stanton, who were first to reach the boys.
He said the signs were good that the group was still mentally well, because keeping their cool was central to their survival. Recent footage, released by the Thai Navy, showed the emaciated boys asking for food and thanking their rescuers.
He said if they had tried to get out by themselves they would have drowned.
Mr Eavis said the type of rescue had been done before, but never with such a large group of young people.
"This situation is unique and uniquely challenging, because it involves so many young people.
"There have been similar situations when people have been brought out with diving gear, when they've never before dived, but they weren't 11 years old and there weren't 12 of them."
He said if they were to dive out, they would have the "very best user-friendly equipment" and at least one diver with them - maybe even two. Neither was it essential that the boys knew how to swim, Mr Eavis said.
"I know one of the best cave divers in the world who can't swim.
"You don't need to be able to swim, but they do need to be able to stay together and keep their minds in the right place.
"They've survived so far without cracking, so the signs are good."
Mr Eavis said the distance to the mouth of the cave was long, but not deep. It would take about 20 minutes to traverse, by a combination of diving and walking in areas where the water level was not at the roof of the cave.
Visibility was not good, but the first divers through had put in a line to help them find their way. They had also had to haul themselves in against the current, so the journey out would be easier.
"It's not all underwater. It's a combination of flooded parts and areas where there's room, so they'll know there's an air space ahead and they'll aim for that."
Mr Eavis said as far as he knew there was no danger in the water rising to the level where the group was resting. He said further rain now would likely make the flooded sections of the cave longer.
"Rising water will make it harder to get them out, but no one needs to panic. They just need to study the weather and make good decisions."
Mr Eavis said the best thing that could happen now was respite from the rain, and they could all be floated out.