The dramatic rescue operation has captivated the country as scores of navy divers, soldiers and police descended on the cave where the young football team and their coach have been stuck since Saturday.
The boys, aged between 11 and 16, went into the cave after football practice and were trapped after heavy rains flooded the chambers and blocked the main entrance.
The group is believed to have retreated to the back of the cave as heavy rains continued to fall, slowly raising water levels inside the complex network in northern Chiang Rai province that spans several kilometres (miles).
After days of desperately searching, officials said yesterday they found a previously undiscovered opening in a section of the cave that they would attempt to helicopter rescuers and food into.
“If we find them, the first thing is to provide first aid and food before thinking of how to bring them back up,” Interior Minister General Anupong Paochinda told reporters.
“We will not stop, we will work 24 hours. We’re racing against time, and we want them to be safe,” he said, adding that the boys had some food with them when they went into the cave.
Helicopters hovered overhead as large crowds amassed around the cave’s muddy entrance, including wailing parents in plastic raincoats who prayed for the team’s safe return.
“I asked for all God’s wishes, but I’m certain in my heart that they will survive. They have been inside the cave before,” the father of one of the young footballers said.
One relative fainted while others waited under a makeshift tent near a shrine with dolls, spiritual offerings and messages for the young boys.
“Please return to your family, please let no harm be done to you,” one mother said in prayer.
The Tham Luang cave near the Laos and Myanmar border is popular among locals who visit in the dry season to worship the small Buddha statues inside.
A sign outside the remote site warns visitors not to enter during the rainy season from July to November when flood risk runs high.
Bicycles, backpacks and football boots were found near the entrance of the cave and divers said on Monday they spotted footprints and handprints in one of the chambers that are believed to belong to the boys.
Continued rainfall has hampered rescue efforts but a new dam 8kg (5 miles) long was being built yesterday to try and prevent more
water from flooding the site.
Electric cables were also laid to provide lighting inside some parts of the blacked out tunnels and an underwater robot was dispatched to survey the area.
The football team, dubbed the “Boars”, are familiar to the area and have previously visited the cave, officials said.
The rescue operation echoed a grim accident in 2007 when eight people were killed as flash floods swept through a cave in Thailand’s southern Khao Sok national park.
Six foreign tourists and two local guides died, while the fiancé of one of the victims survived by clinging onto a ledge for 21 hours.
Thailand Prime Minister Prayut Chan-o-cha said yesterday additional security forces were deployed to the scene and he called for national prayers.
“I want the media and everyone to support the children and coach and wish for their safety,” he said.