THAM LUANG CAVE, Thailand — Searchers trying to reach a dozen boys and their soccer coach in a flooded cave complex used huge pumps to reduce the water level, allowing divers to place guide ropes and air tanks along the route, officials said Sunday.
It was the first significant progress in several days in the massive effort to reach the boys, aged 11 to 16, and their coach, 25, who have been missing in the cave complex in northern Thailand for more than a week. Rising floodwaters in the cave had stalled the search-and-rescue operation for days.
Given how long the boys and their coach have been missing, the odds of finding them alive seemed to be growing thin. But the governor of Chiang Rai Province, Narongsak Osottanakorn, who is overseeing the search-and-rescue operation, expressed hope that Thai Navy SEAL divers could soon reach the cavern where the group is believed to be.
“We are very happy with the result,” he said Sunday. “The water level is reduced, and it makes it easier for the SEALs.”
Tham Luang Cave, a popular destination for cave explorers, is well known for flooding during the rainy season, which generally runs from July to November. The boys and their coach entered the cave system on June 23, shortly before a heavy rainstorm began. Rising floodwaters trapped them several miles inside.
The ensuing search-and-rescue operation, involving hundreds of people from some 20 government agencies and half a dozen nations, has captivated Thailand, with people across the country, including the king, following the developments.
The United States sent a team of 17 Air Force rescue specialists based on the Japanese island of Okinawa to aid in the search, along with additional support staff. Groups from Australia, Britain, China, Laos and Myanmar are also assisting in the operation, as are several Thai companies, including the country’s biggest oil and gas exploration firm.
In recent days, heavy rains in the surrounding mountains have stymied efforts to reduce the water level in the cave complex so that divers could make their way deeper into it. Mr. Narongsak said a break in the rains and increased pump capacity had helped this weekend, enabling the divers’ progress.
“You can see that our officers are smiling and happier than in the previous days,” he said.
Mr. Narongsak said that divers were able to reach a spot known as the third chamber, about a two-hour journey from the entrance, where they established a forward base with lighting, food and extra air tanks.
Divers were eventually able to get about a third of a mile beyond the chamber before a mudslide forced them to turn back, he said.
But the water level was still so high that divers did not manage to repeat the progress they made on Tuesday, when they succeeded in traveling farther into the cave complex, he said.
Rear Adm. Arpakorn Yokongkaew, commander of the Naval Special Warfare Unit, said that the divers were setting up guide ropes to make it easier to get through the dark cave and its occasional whirlpools.
“The most important thing right now is to find the boys,” he said. “Sometimes when we dive we face obstacles and have to retreat. We now will go all the way forward.”
The governor told reporters that an army doctor, the only physician in Thailand who is also trained as a Navy SEAL diver, was at the scene and was prepared to enter the cave to treat any survivors before they are moved.
Experts have prepared special foods that officials say could help the boys and the coach recover after going hungry for many days.
“The food is similar to the food given to astronauts,” Mr. Narongsak said. “They can eat just a bit — but they will get nutrition, and it is high in protein.”
Rescuers also have been working on a plan to bring survivors, who at best would be very weak, out through the flooded cave.
“They have to be in stable condition to be ready to come out,” he said. “The doctor, who can dive, will go in to make an assessment and solve the problem for us.”
Rescuers ran drills over the weekend to practice the extraction operation and encountered several problems. For one, there were so many vehicles on the narrow roads leading to the cave that the ambulances could not get out.
“I have to say that this is the first time in Thailand that this kind of incident has happened,” the governor said. “So, everything is a lesson learned for us.”
Ryn Jirenuwat reported from Tham Luang Cave, and Richard C. Paddock from Bangkok.