With rain forecast as early as tomorrow, Thai rescuers are working round the clock to drain as much water as they can from the flooded Tham Luang cave, as officials mull over options to get the trapped football team out.
Chiang Rai provincial governor Narongsak Osottanakorn, who is leading the rescue effort, yesterday described it as "a race against the water". He said: "Our biggest concern is the weather. We are calculating how much time we have if it rains, how many hours and days."
More generators were taken to the cave system yesterday to power the industrial pumps draining about 1.6 million litres of water per hour - enough to fill over half an Olympic-sized pool. That has reduced water levels inside by 1cm an hour, amid clear weather since Tuesday.
Officials said water has been pumped out from the entrance to the cave's "chamber three", a large space where the Thai Navy Seals have set up a rescue base camp.
That area is still about 3km from where the 12 Thai youngsters and their assistant football coach from the Moo Pa (Wild Boars) Academy were found on Monday, 10 days after they went missing on June 23.
Officials hope enough water can be drained out to allow the group to crawl out at least part of the way.
If sections of the cave remain flooded, the group would have to dive through murky waters and narrow passageways for long distances to get to the entrance.
The meteorological department warned that up to 60 per cent of the country's north, including Chiang Rai, can expect heavy rain from tomorrow until next Wednesday.
Thai officials said yesterday it might not be possible to wait until the boys completely recover before bringing them out, because the rain could hamper the rescue efforts.
The boys, aged between 11 and 16, are unable to swim and have no diving experience, so Thai Navy Seals have been teaching them to do so.
"It takes six hours to get to where the children are and five hours to come back (to the cave's entrance)," said Major-General Chalongchai Chaiyakum, deputy commander of the Third Army Region.
Mr Doytibet Duchanee from the local Sangthum Rescue organisation told The Straits Times that even with experts' help, diving in such difficult conditions would be a daunting task. "The boys will have to use the full-face masks. For inexperienced divers, they might hit their masks against the rocks and the water can get in. They would also have to make their way through the dark."
PM Lee offers Singapore's help
Prime Minister Lee Hsien Loong yesterday welcomed news that the Thai team has been found, and said he has offered Singapore's assistance to Thailand.
In a post on his Facebook page, Mr Lee wrote: "I was happy to hear that the 12 Thai boys and their soccer coach were found safe after being trapped in Tham Luang cave for nine days. The grit and resilience of these young men is an inspiration to all. I hope that the operation to bring them out of the cave will be successful and they can be reunited with their families soon."
He said the gruelling search operation would not have succeeded without the strong leadership of the Thai government and the tireless efforts of the multinational rescue team, including the two British volunteer divers who first found the boys.
"I have written to PM Prayut Chan-o-cha to commend the Thai government's efforts, and to offer Singapore's assistance in any way we can," he added.
He added: "There are hundred of divers here to make sure the boys are safe, but we cannot control whether or not they will get frightened under the water."
Mr Doytibet, who is part of a back-up unit sending supplies to the Thai-led, multinational rescue teams, said the water temperature is below 10 deg C, which could affect the boys' physical condition.
In the meantime, a team is also working on finding an alternative route to bring the boys out through a shaft from the jungle above the cave. On Wednesday, a team of bird's nest collectors from the southern province of Trang, who are experts in rock climbing and exploring caves, were called back into the area to help with that effort.
The boys, who are believed to be about 1km below the surface, said they have heard the sound of a rooster crowing in the morning from above them, sparking hopes that there could be a faster way to extricate them. A video on Wednesday showed the boys in good spirits despite their ordeal.