Samarn Poonan, 38, a former member of Thailand’s elite navy SEAL unit, died on Thursday night as he laid oxygen tanks along a potential exit route deep underground, the SEAL commander said.
Admiral Arpakorn Yuukongkaew said: “We won’t let his life be in vain. We will carry on.”
The tragedy highlights the dangers of the 12 trapped boys being able to escape – none of them can dive and many are unable to swim.
The group, aged between 11 and 16, went missing with their 25-year-old soccer coach on June 23, when they got caught in flashing flooding while exploring.
They were found hungry and frail earlier this week but otherwise in good health.
Rescuers now have to figure out the best options to get the group safely out through several kilometres of dangerously flooded tunnels.
One option had been to keep the 13 inside the cave until the flood waters recede at the end of the rainy season in about four months.
But fears are growing for their safety as heavy monsoon rains are forecast for next week in most of the north, according to Thailand’s meteorological department.
Officials are also considering whether it is possible to drilling a shaft into their cave chamber from the forested mountain above.
Here is the latest news and live updates. All times in BST.
1.38pm update: Fears the boys’ safe place could cave in from drilling
The muddy bank where the boys are stranded is 2.5 miles from the front entrance of the cave, with sections of the final mile stretch now completely underwater.
The boys cannot swim but are being taught how to use Scuba equipment in a bid to free them – but the option of diving them out is deemed risky, to say the least.
There were plans to drill down into the cave from above.
But drilling down raises concerns that parts of the cave could collapse on the boys.
Efforts to widen diving channels have raised similar fears about blocking narrow passageways and hemming the team in.
1.11pm update: Rescue mission hits a dead end
Chalongchai Chaiyakum, a senior Thai army officer, said that one team travelled some 300 metres down a shaft on the hill on Thursday until they reached a dead end.
He said that up to 200 people are exploring the hill to try to find a workable shaft.
12.38pm update: The Thailand cave search comes as rescuers are also hunting for those missing in a boating incident
Rescuers in Thailand deployed helicopters on Friday in a search for 29 people still missing after the sinking of a tourist boat off the island of Phuket, as the death toll in the incident rose to 27.
The Royal Thai Navy said “quite a few bodies” were found in the vessel.
The Phoenix capsized and sank in rough seas on Thursday carrying 105 passengers, comprised of 93 Chinese tourists and 12 Thai crew and tourist guides.
11.15am update: Rescue teams ‘are close’ to saving the boys
Rescue teams thrashed through dense forest hundreds of metres above a cave complex on Friday, searching for an alternative way to extract the group.
Their work above the Tham Luang cave near Thailand’s northern border with Myanmar took on added urgency as forecasts for rain threatened a plan to bring the boys back through cramped, water-logged passageways to the cave entrance.
“We want to find the way down. I believe we are close,” Thanes Weerasiri, president of the Engineering Institute of Thailand, told Reuters at a makeshift camp for volunteers and media near the cave.
9.06am: What are the current rescue options?
The boys are currently being taught how to swim and dive by experts but the death of Mr Poonan has highilghted the danger and huge complexities surrounding such an attempt.
Admiral Apakorn Yuukongkaew, commander of the SEALS unit, told reporters today: “The conditions in the cave are tough.”
One narrow section of the tunnels would involve each boy having to dive alone, which is considered extremely risky.
Other options being considered include keeping the 13 inside the Tham Luang cave until the flood waters recede, at the end of the rainy season in about four months.
But if heavy rains do fall, as are currently predicted for next week, there is a danger that the cave chamber could be at risk of flooding.
Another possibility would be to find an alternative way into their chamber, such as drilling a shaft into the cave from the forested mountain above.
Thailand cave rescue: The 12 boys are close to being saved
8.33am: Volunteer warns rescue attempt could become ‘catastrophe’
Devastated volunteers have been coming to terms with the death of Mr Poonan, with some voicing concerns about the danger of getting the 12 boys and their coach out safely.
Israeli volunteer Rafael Aroush said: “A navy SEAL just passed away last night. How about a 12-year-old boy that will have to pass through?
“There will be rain and many things could go wrong. I don’t want to say it, but it could be a catastrophe.”
8.20am: Prime Minister Prayuth Chan-ocha offers condolences
Prime Minister Prayuth Chan-ocha has offered his condolences over the death of navy seal Samarn Poonan, 38, but said the rescue attempt will continue.
Former Thai navy diver Mr Poonan lost consciousness as he attempted to lay oxygen tanks in a possible exit route for the 12 boys and their coach.
He was about 1.5km from the cave entrance when tragedy struck and died despite his five buddy’s attempt to revive him.
5:11am update: Monsoon rains threaten rescue effort
Torrential rain is predicted this week which could cause even further problems.
Provincial Governor Narongsak Osotthanakorn said the mission was “a race against the water”.
He said: ‘Our biggest concern is the weather.
“We are calculating how much time we have if it rains, how many hours and days.”
4:10am update: ‘The situation has changed’ says commander
Navy SEAL commander Rear Admiral Apakorn Yookongkaew said: “We’ve never experienced this but it’s a mission we have to do. We can’t wait because it’s urgent. We thought the kids would be able to remain there for a while but the situation has changed.”
3:54am update: Diver dies from lack of oxygen on Thailand cave rescue mission
A navy seal has died while trying to rescue children and their football coach trapped in a cave in Thailand, according to Thai authorities.
One rescue diver has died
2:55am update: Multibillionaire Elon Musk wants to help rescue the Thai football team stuck in a cave
Elon Musk, the South African-born entrepreneur with ambitious plans to colonise Mars, has expressed his desire to help Thailand rescue a football team that has been stuck in a cave for the past 12 days.
The billionaire’s team is said to be talking with Thai authorities about the possibility of using SpaceX and Boring Company technology to help rescuers retrieve the young players and their coach from the depths of the Tham Luang Nang Non cave complex.
1:52am update: Monsoon rains could trap boys within hours
Rescuers are running out of time to free 12 boys and their football coach, who are trapped in a flooded cave in Northern Thailand, as monsoonal rain that could force the water level up, is expected to hit the pocket where the group took refuge within hours.
A total of 13 sets of diving equipment have been prepared for the group, who have so far endured 12 nights underground in the Tham Luang cave complex.
1:05am update: Two team members narrowly missed out on disastrous cave trip
Two young members of the Thai football team currently trapped in the cave narrowly avoided disaster because they couldn’t go on the post-training picnic.
Songpol Kanthawong, 13, did not take a bike to practice that day. Thaweechai Nameng, 13, was ordered by his parents to return home to catch up on his homework.
00:23am update: Trapped Chilean miner sends message of hope to boys
A Chilean miner who was trapped underground for 69 days in 2010 has said that the mission to rescue the young Thai footballers will “no doubt” be a success.
Mario Sepulveda said on Twitter: ”I would like to send greetings and a lot of strength to the authorities and the families of these 12 children,” said Mr Sepulveda.
“I have no doubt that if the government of that country puts in everything and makes all the humanly possibly efforts, this rescue will be successful. May God bless you!”
Caitlin Doherty takes over reporting from Georgina Laud
Thursday July 5
10.32pm update: What are the rescue options for the boys?
Given the twisting channels out of the caves, it has taken divers over six hours to travel from the cavern entrance to the boys.
None of the boys can swim, or dive, and so are being given basic swimming lessons should they need to dive to leave the caves.
However, the youth soccer team have also been given four months supply of food, suggesting one option could be to wait until monsoon season has ended before they are rescued.
9.21pm update: Have the boys been able to speak with their families?
Since they were discovered on a shelf above floodwater, rescuers have been supplying the soccer team with food, water and blankets.
There was an attempt made to bring a mobile phone into the cave, however the bag that was holding the phone broke.
Currently, rescuers are debating how to run a cable through the water into the cave to enable the young boys to speak to their anxious parents.
Navy seals had been searching for the missing soccer team for nine days before they were found
9.00pm update: The youth soccer team are in a perilous position due to monsoon season.
It is currently monsoon season in Thailand, a time when rainfall increases exponentially.
Monsoon season begins in May and lasts until November, meaning the boys could possibly be trapped for four months.
Flash flooding caused the team and their coach to become trapped, and could add to the length of time they remain in the dark cavern.
8.00pm update: How far would the boys need to travel to escape?
The trapped boys and their football coach face about 2.5 miles of flooded snaking caves between them and their escape.
Currently they are situated above water level, but continuing rains could cause their situation to become perilous.
It is monsoon season in Thailand, and heavy rains are forecast for this weekend.
The monsoon season could see the cave network flooded for up to four months.
6.30pm update: Why will it take so long to rescue the boys?
The 10km Tham Luang cave complex in Chiang Rai is relatively unexplored and includes narrow, dark passages.
Before the boys reach a T-junction three km north of the cave’s entrance they will have to dive at leat once, said rescue workers.
Major General Chalongchai Chaiyakum, deputy commender of the Third Army Region said: “It takes six hours to get to where the children are and five hours to come back (to the cave’s entrance).”
Some of the boys can’t swim, which has caused rescuers to have to try alternative methods of rescue such as pumping water from the caves.
4.45pm update: Forecasted rains threaten the safety of the boys even further
A downpour is expected to hit Thailand in the area where the boys and their football coach remain trapped.
There has been a dry spell in recent days, however, monsoon rains are forecast for Sunday, potentially causing more danger for the trapped boys if water levels rise further.
Chiang Rai Governor Narongsak Osotthanakorn said they were “racing against water”.
“We are calculating how much time we have it if rains, how many hours and days,” he said.
4.00pm update: How much water has been pumped out of the cave complex so far?
Rescuers have acted quickly during a spell of dry weather and have pumped water away from the cave complex where the boys are trapped.
As of today, around 128 million litres of water has been pumped from the caves, which has seen water levels decreasing at a rate of 1.5cm per hour.
Rescuers have created a 1.5-mile long area in the caves from the entrance, which they are able to walk through.
Thailand cave rescue: The 12 boys have been found
3.45pm update: What should you do if you get stuck in a cave?
John Hudson is a survival instructor, broadcaster, writer, public speaker and training consultant who created the UK Military’s survival manual.
Speaking exclusively to Express.co.uk, he said the fundamental difference between life and death in these situations is letting someone know what you’re up to.
“If there’s any element of risk, you need to let someone know where you’re going,” he said.
“We should be able to get out there and stretch ourselves, not sit on the sofa, but you need to let someone know where you’re going and when you’re expected back.”
Mr Hudson added there’s little use doing this if you haven’t done your research into who would come to your rescue.
“You need to have told your mates who to call if you disappear,” he said.
3.40pm update: The boys are not well enough to be saved
Seven Thai Navy SEAL divers, including a doctor and nurse, spent Tuesday night with the Wild Boar soccer team.
Despite being trapped for almost two weeks, a medical assessment has now concluded they are not well enough to move at this stage.
Two of the boys and the coach are said to be suffering from severe malnutrition and exhaustion.
None of the boys can swim or dive and the cave system is still mostly flooded.
The boys are receiving rudimentary dive training and swimming lessons now while they wait, but there are fears that if conditions don’t improve they may be stuck there for months while monsoon season passes and the water drains.
The military are trying to pump out as much water as they can but efforts are hampered by rains as the monsoon season continues.