Snaking up a hillside along a steep jungle track, a convoy of trucks loaded with dozens of Thai rescue workers churns through mud on what’s become a daily mission to find an alternative route out of the Tham Luang cave.
The group of nearly 50 military and government personnel is searching for entrances in the mountain, natural chimneys that could be used to access 12 boys and their coach, who have been trapped by flood waters inside the cave for almost two weeks.
The death of an experienced diver in the cave system Friday underscores the risk of attempting to move the boys, who are physically weak after days without food, through the flooded main entrance.
The Thai soldiers and National Park Authority workers drive 20 kilometers (12 miles) from the cave’s main entrance in Mae Sai to Doi Pha Nee, a mountain northwest of the main entrance of the Tham Luang cave system, near Thailand’s border with Myanmar.
Searching for an entrance
There, they search for holes worth exploring by a team of expert rock climbers who have flown in from south Thailand to help. Other Thai military officials, forestry guides, village elders and other local experts are on hand to offer guidance on navigation and terrain.
CNN accompanied the teams Thursday as they plowed through steep muddy lanes to reach area of lush grassland. There, they finalized the plan for the day over balls of sticky rice and pork and the popular Thai energy drink M-150.
Armed with GPS coordinates, team leaders pinpointed on a map where they thought a key chimney might be. The group then set off, trekking along dirt paths through farmland and scrambling up a hillside through jungle.
The teams split into smaller groups to survey the area for possible cave entrances. Before long, a whistle blew to summon the rest of the team. One of the trekkers had found a cave entrance in a rocky part of the hillside. The climbers came to check it out, but it was quickly dismissed.
Moving on to higher ground, another opening was soon discovered. This time it seemed more promising and the group geared up to investigate it properly.
Superfit and apparently fearless, the climbers squeezed themselves into the dark crevice and gradually disappeared one by one into the cave. For them, this is not just a hobby: they earn their living as some of Thailand’s infamous bird’s nest collectors.
This controversial practice involves collecting the nests of rare birds from cliff faces and caves to provide the ingredients for one of the world’s most expensive dishes: bird’s nest soup, a delicacy in China.
The team of six of the climbers managed to descend 300 meters (980 ft) of rope. Their GPS calculations suggested that the boys were only another 300 meters away. But disappointed voices reached the surface.
“It’s a dead end,” one of the group said
The team trekked on to 800 meters (2,600 ft) above sea level in search of entrances higher up the mountain.
Hiking uphill in temperatures in excess of 30 degrees Celsius (86 Fahrenheit) with humidity at over 90% while carrying heavy equipment and ropes made for a grueling, sweat-soaked hunt.
In the midst of a farmed area of giant banana trees and coffee plants, the group came across another search team of soldiers and cavers.
“We came with the Thai military team to look for holes and caves and to see if they go deep enough,” said Mario Wild, a 38-year-old Austrian caving instructor from Chiang Mai Rock Climbing Adventures. “So far, no success.”
His colleague, 31-year old Add Kongsingh, said other people in the area were trying to help in similar ways.
“We have some experience with caving. We have been searching around these mountains, trying to find a potential hole that we think can connect,” said Kongsingh.
Their team has been out every day this week. But Kongsingh is worried that time is running out fast for the boys trapped deep in the mountain, where the risk of rising water poses a potentially fatal threat.
“I think rain is coming in the next couple of days,” he said.
CNN’s Kocha Olarn contributed to this report.