BANGKOK — Rescue workers were searching a large cave network in northern Thailand on Monday in the hopes of finding 12 boys and their soccer coach, who have been missing for two days.
Heavy rains have flooded a narrow passage leading into the cave complex, blocking the group’s exit and complicating rescue efforts, officials said.
The drama of the rescue attempt has dominated television news and social media in Thailand, and King Maha Vajiralongkorn Bodindradebayavarangkun was said to be following the rescue efforts.
The complex, in Chiang Rai Province near the border with Myanmar, is known as Tham Luang Nang Non and is a tourist attraction during the dry season, which usually ends in April.
Divers with a Royal Thai Navy special operations unit used scuba gear to make their way through the flooded passage late Monday afternoon and were searching the main chamber of the cave for the local boys, ages 11 to 16, and their coach, 25.
The deputy governor of the province, Passakorn Bunyalak, said he was confident the group was still alive.
“The kids are athletes, and they have skills,” he told reporters. “They are alert all the time. And they are always active. They will try to survive by continuing to move.”
Parents reported the boys missing when the group did not return from team practice Saturday afternoon.
Bicycles, soccer shoes and other equipment were found at the entrance of the complex, which has only one way in and out. Fresh footprints and handprints were found inside, Mr. Passakorn said.
In the past, visitors have gotten stuck in Tham Luang during similar conditions and have survived for days before being rescued.
A stream runs through the cave system, and the authorities said they were worried that heavy rainfall could cause a flash flood, endangering everyone inside.
A sign outside the cave’s entrance warns visitors not to enter at this time of year, when rains are expected.
“Our concern is about the rain,” Mr. Passakorn said. “The water inside the cave keeps rising.”
He said the air in the cave system was very thin. The authorities told anxious villagers to stop burning incense at the cave entrance for fear it would deplete the oxygen inside.
Rescue workers were able to enter the five-mile-long cave complex on Saturday and Sunday but could not locate the boys and their coach, who are from various villages in the Mai Sai district, near the cave.
If the Navy divers find the group and the water levels remain high, they may have to teach them basic scuba techniques to get them out, he said. Rescue workers were also bringing in pumps that could be used to lower the water level, he said.
“We always have hope,” he said.
Ryn Jirenuwat contributed reporting.