The operation to free 12 boys and their coach trapped in a cave in northern Thailand is running “smoothly”, the head of the operation says.
Four boys have been brought above ground so far in good health, rescuers say.
The mission has now been paused for at least 10 hours as air tanks need to be replaced.
Rescuers decided to go ahead with the hazardous operation on Sunday because of fears of rising waters.
The next phase would begin on Monday morning, after relaying “all of the air tanks and all systems along the way”, Chiang Rai Governor Narongsak Osottanakorn said.
He corrected earlier reports that said six boys had been freed.
Divers have been guiding the boys through darkness and submerged passageways towards the mouth of the Tham Luang cave system. They have reportedly been able to make the last part of the journey on foot.
Rescuers took advantage of a break in the rain to launch the mission much earlier than originally expected.
The first phase has also been conducted much faster than officials had predicted.
The group and their families had all given their agreement that they should be moved as soon as possible, said Mr Narongsak.
A team of 90 expert divers – 40 from Thailand and 50 from overseas – has been working in the cave system.
Getting to and from where the boys are has been an exhausting round trip, even for the experienced divers.
The process includes a mixture of walking, wading, climbing and diving along guide ropes already in place.
Wearing full-face masks, which are easier for novice divers than traditional respirators, each boy is being accompanied by two divers, who also carry his air supply.
The toughest section is about halfway out at a section named “T-Junction”, which is so tight the divers have to take off their air tanks to get through.
Beyond that a cavern – called Chamber 3 – has been turned into a forward base for the divers.
There the boys can rest before making the last, easier walk out to the entrance. They are then taken to hospital in Chiang Rai.
In an indication of how dangerous the journey can be, a former Thai navy diver died in the caves on Friday. Saman Gunan was returning from a mission to provide the group with air tanks when he ran out of oxygen.
He lost consciousness and could not be revived. His colleagues said they would “not let the sacrifice of our friend go to waste”. (Excerpts from BBC)