Rescue divers inched closer to a spot in a flooded cave where 12 boys and their football coach have been missing for more than a week after days of bad weather beset the grueling search.
Rescue divers cleared a key hurdle on 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.
The search picked up pace Saturday, as a break in the rain eased flooding in the system of caverns and more experts from around the world joined the rescue mission.
A team led by Thai navy SEAL divers pushed through the murk of a kilometre (half-mile) long chamber to a passageway that could lead to where the missing may have taken shelter, said the SEALs' commander, Rear Adm. Arpakorn Yookongkaew.
But Arpakorn said even though the divers made some progress in their effort to find the missing, they're not yet where they want to be.
"It's still tough as the water stream is quite strong," he said.
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.
"Today we made good progress, and it was a positive improvement, very positive," Chiang Rai Gov. Narongsak Osatanakorn told reporters.
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.
Eight days into the search, there has still been no contact with the boys, aged between 11 to 16, or their 25-year-old coach who entered the sprawling Tham Luang Nang Non cave after a soccer game on June 23, but near-constant rains have thwarted the search for them.
Authorities have nevertheless expressed hope that the group has found a dry place within the cave to wait, and that they are still alive.
Reflecting that hope, a medical evacuation drill was held Saturday morning to see how long it would take to get rescued people out of the cave, into 13 ambulances and to the nearest hospital.
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," Gov. Narongsak said. "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.
Navy divers had still to navigate their way through three km (nearly 2 miles) of dark, flooded cave passages on Sunday to reach the spot rescuers believe would give 12 missing boys and their soccer coach a better chance of survival.
With the boys' way out blocked by flood waters from the heavy rains, rescuers are hoping that they made it through to an elevated rock mound in one of the underground chambers far under the mountain. Cavers have nicknamed the potential safety spot "Pattaya Beach" after one of Thailand's best known tourist destinations.
Rear Admiral Apakorn Yuukongkaew, commander of Thailand's elite navy SEAL unit said divers had reached 'chamber three', having been driven back by rising floodwaters when they reached the same point earlier in the week. "From chamber three to the intersection and then onto Pattaya Beach, this area is all flooded and dark," Apakorn told reporters. "It's about 3 kilometers from chamber 3 to Pattaya Beach."
Dr Somsak Akkasilp, director-general of the Medical Services Department, said the group's survival depended on whether they found fresh drinking water, but he was concerned about the risk of infection from unclean water, or contact with some animal inside the cave.
"They should be okay without food for eight days," he said.
Rescue teams have also been scouring thick jungle on the mountainside for alternative routes into the cave.
Helicopters were seen flying over the cave complex on Sunday morning dropping supplies to police and other rescue teams that camped there overnight.
On Saturday, members of a police search team were lowered down a 50-metre shaft drilled from the surface to the cave, but it was unclear what progress they had made.
"Today is a bright day for me and our team. We have sunlight today, roads are easily walkable," Narongsak Osottanakorne, governor of Chiang Rai province, told reporters on Sunday afternoon.
He said water levels in the cave had decreased and that almost 60 foreign and Thai divers were involved in the rescue effort.
"Today what we have to do is to rush to the kids," Thai Navy Seal commander and Rear Admiral Apakorn Yookongkaew said earlier at the site. "We will not stop until we find them."
Responders are placing extra oxygen tanks, strong ropes and LED lights along the cave's walls in hopes they can provide a path to an airy chamber called Pattaya Beach where officials believe the 13 are taking refuge because of its elevation.
Rescuers have advanced 600 metres from the base towards the Pattaya site, while heavy drilling at separate chimneys outside the cave has started in an attempt to establish communication with the boys.
"I'm feeling happy like I've never felt in a long time. Many good signs," the football team's head coach Nopparat Khanthavong, 37, told AFP on Sunday.
"The rain has stopped and rescue teams have found potential ways to reroute the waterway", diverting its flow so no more enters the cave, he said. "The families are feeling much better too."
"Every single day the conditions are changing," Jessica Tait, a spokeswoman for the US troops, told AFP. "With the improvement with the weather, hopefully some other areas and some of the efforts are becoming easier."
"We still expect some difficulties, because we have to drill not vertical, but inclined," Suthisak Soralump, a geotechnical engineer leading up the effort, told AFP. "But anyway we put our best team in Thailand to come. So let us try."
Officials said Friday that they were dropping care packages into the shafts in hopes the missing might retrieve them. Each package contains food, beverages, a phone, a flashlight, candles, a lighter and a map of the cave.
Aside from bicycles and soccer boots left near the cave's entrance, and some handprints seen on the walls, the searchers have found no trace of the boys, aged between 11 and 16, or their 25-year-old assistant coach.
As the search for the boys hit its eighth day, attention turned to their chances of survival inside the cave with little or no food and light.
The group likely has access to fresh water -- either dripping in through rocks or rushing in through the entrance -- but experts warned that runoff water from nearby farms could carry dangerous chemicals or bacteria.
"If they drink the water in the caves and it makes them sick it could hasten the problem that they are in, but if they don't drink it then they are also in trouble," Anmar Mirza, coordinator of the US National Cave Rescue Commission, told AFP.
But even without food he said young, athletic boys could "easily live for a month or a month and a half" with the main challenge their mental resolve.
"The biggest issue that they are facing right now if they are alive is psychological because they don't know at what point they might get rescued," Mirza said by phone from the US state of Indiana.
Andy Eavis, retired head of the British Caving Association and one of Britain's most accomplished speleogists who has led numerous sub-terranean exploratory expeditions around the world, says it's just a matter of time before the group is found.
Stretching 10 kilometres (six miles) and with complicated, snaking pathways and narrow corridors, Tham Luang is one one of Thailand's longest and toughest caves to navigate.
Officials said the boys know the site well and have visited many times before, buoying hopes that they might have trekked to a large airy chamber in the centre.
Rescuers found footprints and handprints in a chamber near that spot earlier in the week, further in from where they found the kids' football boots, backpacks and bicycles.
Relatives kept a vigil, with prayers led by a Buddhist monk, near the mouth of the cave.
"I am still hopeful and hope the children will come out safely," Kampon Paree, 39, an uncle of three of the missing boys, told Reuters.