THAM LUANG CAVE, Thailand — The British diver John Volanthen was placing guide lines to try to get closer to 12 missing boys and their soccer coach trapped in a flooded cave network when he ran out of line himself, forcing him to the water’s surface.
There they were, all 13, staring at him through the light of his headlamp. After 10 days of efforts racing against monsoon rains and rising water in the cave, the search for the missing soccer team had finally succeeded.
If his line had been even 15 feet shorter, he would have turned back and not reached them on that dive Monday night. The group would have spent at least another night on its own in the pitch black, not knowing if a rescue would ever come.
“Literally, he finished his line, stuck the line reel in the mud, and they were looking down,” Vernon Unsworth, his friend and fellow cave explorer, said Tuesday.
With the search officially turning to a rescue operation on Tuesday, the main question now has been the best way, and the best time, to get the boys and their coach out of the cave.
Capt. Anand Surawan of the Thai Navy raised the possibility that, under the worst-case scenario, the 13 would be in the cave for four months until the end of the rainy season.
“I was surprised myself,” said Supanat Danansilakura, chief of public relations for the Royal Thai Navy. “Four months?”
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Others argued that it would be hard on the boys and dangerous to leave them in the cave for so long, even if they had light, food and other supplies. They could be injured or risk infection and be harmed psychologically by a prolonged stay in such an environment.
The fact that officials and relatives of the boys were able to even discuss the best way to extract them is itself remarkable.
The boys, ages 11 to 16, and their 25-year-old coach disappeared into Tham Luang Cave on June 23 after a Saturday soccer practice. Heavy rain then began to fall, and water rose in the cave complex, blocking their exit.
“When we first discussed this mission, we said right away this mission is impossible,” said the governor of Chiang Rai Province, Narongsak Osottanakorn, who is overseeing the search and rescue operation. “In English, it will be mission impossible, like the movie. But the SEALs were very confident in their ability, and they told us they would bring the boys out.”
The Thai government mounted a huge rescue operation and sent scores of divers into the cave to try to reach the area where the boys were believed to be. A top official said they would spare no expense.
A country that often appears divided between the rural poor and the urban elite found itself united by the hope of finding the missing boys. King Maha Vajiralongkorn Bodindradebayavarangkun took a personal interest in the search, sending kitchen trucks to feed the search crews and raincoats to protect them from the downpour.
Half a dozen countries sent teams to help, including the United States, whose team of 30 included 17 Air Force search-and-rescue specialists.
Relatives of the missing spent much of the 10 days of the search waiting for news in plastic chairs under a temporary awning near the operation’s command center.
They jumped and shouted with glee on Monday night when they heard that the group had been found. By then, Thai officials had moved the relatives indoors to a private area, and the throng of journalists covering the search have mostly been kept from speaking to them.
Tham Luang Cave has been a daunting challenge. The seven-mile-long cave system is simple enough to hike and climb through during the dry season. But in the rainy season — in theory from July to November — the complex can fill with water, submerging many of its passageways.
Divers finally had a breakthrough, literally, when they chipped away at rocks and enlarged a passageway that had been too small to pass through while wearing an air tank.
Once they had created a large enough opening, they were able to push on to where they suspected the group was, roughly three miles from the cave entrance.
Mr. Volanthen and Rick Stanton, both civilian British divers, happened to be in the lead Monday night, laying the guide ropes that divers can use to pass through the murky or turbulent water.
It was when Mr. Volanthen ran out of line and surfaced that he saw the group of scrawny boys, some sitting, some standing, on a shelf above the water line.
He was relieved to find all of them alive. The boys were excited about the prospect of food.
“Eat, eat, eat,” one of the boys called out.
The two divers set up a pair of dive lights to illuminate the cave, no doubt the first light the group had seen in days.
It was the first of many deliveries of needed supplies, including food and medicine, over the next 24 hours.
“At the beginning, we had only hearts and manpower,” the governor said. “Lately we have all the resources. Even though we are tired and weary, we are fully equipped.”
Medical teams were giving the group high-protein food to help them regain their strength. And they were assessing how soon the trapped team would be in shape to move out of the cave.
Mr. Unsworth, a caver from Britain who lives nearby and has been exploring Tham Luang Cave for more than six years, said it would be far better for the boys to be taken out immediately by experienced cave divers than to be forced to wait for months.
“It is just the logistical thing of how to get them out, because they have never dived before,” he said. “They will have to learn very quickly, like in the next few hours. If not today, it could be tomorrow.”
He said the boys could use full face masks so they would not have to learn how to breathe through a demand valve, which most divers use.
Thai Navy SEAL divers and other experienced cave divers participating in the rescue should be able to take them safely through the cave system’s flooded passageways, he said.
Leaving them underground until the end of the rainy season, he said, “is not an option.”
Mike Ives contributed reporting from Hong Kong.