Thai rescue team members head back inside a cave where 12 boys and their soccer coach are trapped.
Rescuers in Thailand are today desperately drilling more than 100 shafts through mountain rock to reach 12 trapped young footballers.
The last-ditch rescue effort is set to take place in the following 'one or two days' as monsoon rains approach — which would make the cave impassable.
Elite navy divers are on anxious standby to rescue the team who have been trapped in a cave for 14 days.
The boys and their 25-year-old coach are not ready to be extracted, but authorities are likely to launch a risky rescue attempt in coming days if rain begins catastrophically flooding the caves.
Chiang Rai Governor Narongsak Osottanakorn said the boys were learning to dive but were not strong enough to undertake to long journey through narrow, underwater passages.
Navigating the cave system takes an experienced diver more than five hours and the boys were not back at full strength after suffering exhaustion and starvation before rescuers found them.
Speaking outside the Tham Luang caves in northern Thailand, the governor ruled out a rescue attempt overnight on Friday but indicated the situation could change in days to come.
'There is no chance the boys will come out today. It is not suitable, they still cannot dive,' he said at a long-awaited press conference after midnight on Saturday local time.
'The children are learning how to dive. We'd like minimum risk, but we can't wait until it rains heavily and worsens the situation.
'If that happens, we'll need to reassess. The key thing is the kids' readiness to dive. If it rains, and the situation is not good, we will try to bring the boys out.'
Officials have long feared the coming torrential rain would catastrophically flood the cave system in Chiang Rai and make rescue impossible.
Should the rains further flood the cave, as predicted, the team could be trapped in the cave for more than four months until waters recede,
However, Governor Narongsak appeared unwilling to let the 12 boys and their coach be stuck for that long, as he laughed when asked if they would be left inside.
He said rescuers 'need to make the plan that is the best plan' and were assessing options, they will then test the plan to make sure it will work with a low enough risk.
'If the risk is minimal, we will try. We are afraid of the weather and the oxygen in the cave. We have to try to set the plan and find which plan is the best,' he said.
But he appeared to rule out tunnelling through the rock to reach them in favour of the boys swimming out in dive gear or being pushed through the tunnel by divers.
'The boys entered through the front of the cave, they will come out through the front,' he said.
Governor Narongsak said the boys were still healthy and have practised wearing diving masks and breathing in preparation for the diving possibility.
When asked if he felt positively about the situation, he replied: 'The world is perfect'.
'I'm worried about everyone who participates in the rescue operation,' he added.
Officials have been planning to fit the boys with full-face oxygen masks and extract them two at a time with navy chaperones.
On Friday, after pumping out 130 million litres, the cave water levels had dropped by enough to enable the boys to pass some sections without going under water. It means that an 11-hour return journey has apparently been cut to less than six.
He said the two British divers had yesterday visited the boys again, who were mostly in good condition, although three were now 'quite weak' physically.
'Weaker than the other boys, but not in a serious condition. And they are all mentally strong,' he said
However, rescue teams are racing against time amid worsening weather and lowered oxygen levels, which may force rescuers to try pulling the boys out before they were fully ready.
'We can no longer wait for all conditions to be ready, because circumstances are pressuring us,' naval chief Apakorn Yukongkaew said.
'At first, we thought the children could stay for a long time, but now things have changed.'
The extreme dangers were brought home on Friday when former Thai navy seal Saman Kunan drowned during the rescue operation's preparations.
The 38-year-old volunteered to help deliver oxygen tanks though a long underwater tunnel, but got into trouble underwater despite being an expert diver and a super-fit triathlon runner.
His death prompted concerns over how 12 terrified children who cannot even swim would fare on the same hideous journey.
Mr Kunan body was flown to his hometown in Roi Et for a royally-sponsored funeral, with pictures showing military officials transporting his flag-draped coffin.
Watching grey skies with terror, their parents can only wait and pray
For the anguished parents of the lost boys, there is nothing to do but wait and pray.
It is now two weeks since their sons walked into the cavern and never came out. Their mothers light incense sticks and pray in front of a statue of Buddha.
But their silent vigil is in stark contrast to the extraordinary scenes developing around them.
For ever since the 12 footballers and their coach were found on Monday deep inside the Tham Luang cave system in northern Thailand, a functioning tented town has sprung up in the jungle around the rescue operation.
Soldiers, police, navy divers, European volunteers, engineers, workmen, government officials and even hairdressers – along with scores of television and newspaper journalists – all squelch through the quagmire.
Field kitchens have been set up with teams of cooks rustling up hot meals for everyone.
Every few hours, teams of exhausted, mud-caked rescuers emerge to enthusiastic applause from the tunnels. A few feet away, the mothers and fathers watch, but don't eat.
Among them are the parents of Prajak Sutham. They have kept a 24-hour vigil since rushing to the remote jungle spot the morning after their 14-year-old son, nicknamed 'Note', failed to return from his excursion.
Note's mother Ratdao Janthapoon, 35, and father Sudsakhon Sutham have vowed to stay as long as it takes – even though officials warn it could be months if they are forced to wait out the monsoon.
Sarisa Promjak, Note's aunt, said: 'My sister has been up the cave since the day after Note went missing and she has been there ever since. She and her husband spend day and night there. Note's dad says he cannot eat. They say they will not leave until their boy is safe.'
A huge pumping operation is under way to reduce the flood levels inside the caverns. Water spurts out of long hoses at the rate of 180,000 litres an hour and gushes down the hillside.
Inside the caves, the water levels are dropping – but agonisingly slowly. Everyone eyes the grey sky with fear, as forecasters predict a week of monsoon rains.
Another problem is sinking oxygen levels inside the caves – down from the normal 21 per cent to 15 per cent – caused by dozens of rescuers being in there. Teams of divers have been transporting canisters into the tunnels to release oxygen.
As Ivan Karadzic, 44, a volunteer diver from Denmark, returned for a second shift yesterday, he said: 'Somebody died and obviously it is a little bit scary going in there. But we have to carry on.'
A plan to run a phone line in has yet to work. Full-face diving masks have been taken in too, with the children undergoing a crash course in cave diving.