Rescue divers cleared a key hurdle Sunday in the increasingly desperate search for 12 boys and their soccer coach who went missing in a cave in northern Thailand more than a week ago, officials said.
A team led by Thai navy SEAL divers pushed through the murk of a kilometer- (half-mile-) long chamber to a passageway that could lead to where the missing possibly took shelter, said the SEAL's commander, Rear Adm. Arpakorn Yookongkaew.
But Arpakorn said even though the SEALs have made some progress in their effort to find the missing, they are not yet where they want to be.
"It's still tough as the water stream is quite strong," he said.
The missing boys, aged 11 to 16, and their 25-year-old coach entered the sprawling Tham Luang Nang Non cave in Chiang Rai province after soccer practice on June 23. They were apparently trapped inside by flooding caused by heavy rain and have not been heard from since.
The divers have been stymied again and again by muddy water rising to the ceiling of the chamber, forcing them to withdraw for safety reasons. When water levels dropped, the divers went forward with a more methodical approach, deploying a rope line and extra oxygen supplies along the way. The teams that swam Sunday included the SEALs, Australian divers and rescuers from the Thai city of Ayutthaya.
The effort had rebounded from earlier Sunday, when it appeared divers were making little progress.
The divers' goal is to get to an area of the cave known as Pattaya Beach. That section of the cave has a higher elevation, and authorities hope it remained dry and the 13 missing took shelter there.
The search has been going slowly, largely because flooding has blocked rescuers from going through chambers to get deeper into the cave. Pumping water out of the cave hasn't solved the problem, so other teams have been looking to divert groundwater.
Other efforts have focused on finding shafts on the mountainside that might serve as a back door to the blocked-off areas where the missing may be sheltering.
Teams have been combing the mountainside looking for fissure that might lead to such shafts. Several have been found and explorers have been able to descend into some, but so far it is not clear whether they lead to anywhere useful.
"We surveyed all areas and there were reported to be about 20, and out of that there are about 10 with the possibility of having shafts," Chiang Rai Gov. Narongsak Osatanakorn told reporters Sunday. "But at the moment, we have narrowed it down to two. Today we are working inside those two shafts."
Experts in cave rescues from around the world continued to gather at the site. An official Australian group has now followed a U.S. military team, British cave experts, Chinese lifesaving responders and several other volunteer groups from various countries.