The British diver who found 12 Thai boys and their coach trapped alive in a flooded cave has described his "massive relief" as he counted them one by one, sparking a rescue bid unprecedented in its daring and complexity.
The young "Wild Boars" and their 25-year-old football coach Ekkapol Chantawong wandered into the cave on June 23.
Sudden floodwaters forced them to retreat deep into the Tham Luang complex, sparking a desperate hunt that seized the world's attention until they were all safely extracted on July 10, after a nail-biting three-day mission.
The success of the rescue operation has even stunned its architects -- expert divers who battled muddy, rushing floodwaters for days to reach the group and eventually extract them.
Richard Stanton, one of a pair of British caving experts who found the boys, gave reporters Friday a first-hand account of the moment he saw them emerge from behind a rock face onto a muddy ledge kilometres (miles) inside the Tham Luang cave.
"That was a massive, massive relief. Initially we weren't certain they were all alive -- as they were coming down I was counting them until I got to 13," he said after his arrival at London's Heathrow airport.
Grainy footage of the moment Stanton and John Volanthen discovered the dishevelled and emaciated group has become the symbol of a remarkable survival story -- that has already piqued the interest of Hollywood film producers.
But the mission would last a further eight days, with the risk of extracting the weakened group through flooded, tight, twisting passageways intensified by the risk of fresh rains and falling oxygen levels inside the cave.
The mission was "an order of difficulty much higher than anything that's been accomplished anywhere around the world by any other cave diving team," said Stanton.
A former Thai Navy diver died trying to establish an airline to the group just two days before the rescue bid was launched.
- Water from stalactites -
The boys are recuperating from their ordeal in Chiang Rai hospital, apparently in good spirits with doctors on Friday saying they were sleeping and eating well and able to receive visits from close relatives.
The father of Duangpetch Promthep, or "Dom", cast light on how their survival hung in the balance in the nine days before they were found.
"When the boys were hungry, coach Ek shone his torchlight up towards the stalactites, telling them to drink the water dripping down," Banpot Promthep told reporters late Thursday.
He said the boys were "ecstatic" when the two divers appeared in front of the ledge where they had sought sanctuary, crowding to the front of the bank to greet their rescuers.
Thai authorities have only released partial information about the bold operation to free the team, heavily restricting access to the boys and their families.
But in a striking coda to an already astonishing tale, a former Thai Navy SEAL told AFP the boys were "sleeping" as they were passed from divers or on pulleys as they exited the cave in stretchers.
Footage circulated by the SEAL team showed boys seemingly unconscious in wetsuits and diving gear being carried over rocky passageways.
Australian anaesthetist and diver Richard "Harry" Harris posted new details of the audacious rescue operation on Facebook, saying he had "never seen anything like it".
"Local climbing and rope access workers rigged the dry cave section for that part of the rescue and scoured the bush for more entrances to the cave.
"Drilling teams attempted to get through nearly a km of rock to the boy's location. And all this time 4 brave Navy Seals sat with the Wild Boars knowing they were in as much danger as the kids," he wrote.
"When it seemed all other options were exhausted, the decision to swim the players out was made and the rescue went ahead."
He added: "The pressure that was put on these (international divers) was immense and they never dropped the ball for a second."
The rescue bid was also lauded for the hard, long hours and teamwork between highly-skilled Thais and foreigners.
"Despite all this amazing technology, in the end it took people working together.... for this one unifying goal," said American caver Josh Harris, 42, who worked as liason between the foreign divers and the Thais.
"In the end, cave rescue requires cavers and trained cave rescuers," he said, referencing the "distraction" of the offer by US tech guru Elon Musk to evacuate the boys in a special pod.
Two British cave divers found the boys more than a week after they went missing
Graphic showing the rescue of a youth football team trapped inside a cave, based on a video released by the Thai Navy SEALs.
The boys were transported through the cave in a complex rescue operation
The boys are recuperating from their ordeal in Chiang Rai hospital