
On damp scraps of paper torn from an exercise book, brief but heartbreaking messages from the boys trapped in a Thai cave offer a slender ray of hope for their desperate parents on the surface.

The chirpy messages of love for their families and longing for their favourite foods are in stark contrast to the darkening mood and sky outside.

The past few days have been relatively dry but with today's forecast of monsoon rain that could flush through the Tham Luang Nang Non cave 'like a tsunami' comes the terrifying realisation that time is running out.

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Elite navy divers are on anxious standby to rescue the Thai football team trapped in a cave for 14 days as monsoonal rain threatens to wreck hopes of saving the 12 schoolboys

Speaking outside the cave, Governor of Chiang Rai province Narongsak Osatanakorn, who is in overall charge of the rescue, said: 'We're trying to pump water out, but more and more is coming in from above and below. Our biggest concern is now the weather.

'A heavy downpour comes down into the caves like a tsunami.'

He added: The children are learning how to dive. We'd like minimum risk, but we can't wait until it rains heavily and worsens the situation.

'If that happens, we'll need to reassess. The key thing is the kids' readiness to dive. If it rains, and the situation is not good, we will try to bring the boys out.'

Chiang Rai Governor Narongsak Osottanakorn said the boys were learning to dive but were not strong enough to undertake to long journey through narrow, underwater passages

Speaking outside the Tham Luang caves in northern Thailand, the governor ruled out a rescue attempt overnight on Friday but indicated the situation could change in days to come

Perhaps oblivious to the desperate race against the elements and that the world is holding its collective breath, the boys in the Moo Pa (Wild Boars) football team urged their families not to worry as they signed off the short letters with their team nicknames.

The youngest member of the party, 'Titan' (Chanin Wiboonroongrueng, 11), wrote: 'Mum and Dad, don't worry about me, I'm fine. Tell my brother to get ready to take me out for fried chicken.' Another, 'Pong' (Somphong Jaiwong, 13), wrote: 'Dear Mum and Dad, don't worry, I'm safe. Love you.'

Another boy writes: 'I'm doing fine. The air is a little cold, but don't worry. Although, don't forget to set up my birthday party.'

Team coach Ekkapol Chantawong, 25, apologised to the parents in his note, saying: 'To the parents of all the kids, right now the kids are all fine, the crew are taking good care. I promise I will care for the kids as best as possible. I want to apologise to the parents.'

The young Thai footballers trapped in the Tham Luang cave have written these heartfelt messages to their parents

Keeper: Ekkarat Wongsookchan, 14, is also known as 'Bew' and is a goalkeeper

Harry Kane fan: The family of Sompong 'Pong' Jaiwong say the sports-mad teenager is cheering on England to win the World Cup

'Ideal defender': Panumas 'Mick' Saengdee, 13 has been praised by his coaches for his skills

The letters were brought out by divers along the tortuously narrow tunnel system – much of it underwater – which separates the boys from safety.

With great dignity, their mothers and fathers have tried to contain their emotions while being housed in a brick-built rangers' station.

They are close to a small army of rescue workers that includes British cave divers Rick Stanton and John Volanthen, who found the boys huddled on a ledge last Monday.

Pipat is reportedly not a player for Wild Boar FC, but had joined the team for practice session before they embarked on their trek to the caves

Leader and newbie: Duangpetch Promthep, 13, left, is the team captain of Wild Boar FC, while Mongkol Boonpiam, 14, right, joined just a year ago

Losing hope:'Ideal defender': Panumas 'Mick' Saengdee, 13 has been praised by his coaches for his skills's mother has said she had thought there was a 50 per cent chance that her son would be found

Experts say there are four options available to the rescuers:

To take the boys out through the flooded cave system wearing scuba gear. This is by far the riskiest solution – especially after the tragic death of former Royal Thai Navy SEAL Saman Funan in the caves on Friday – but if the rescuers think a deluge will completely flood the caves, there is no alternative.

To continue the mammoth pumping operation that is removing 13,000 litres an hour in the hope of lowering the water level enough to allow the boys to escape on foot before the monsoon rains begin.

To simply wait until the end of the monsoon season in October when the caves will drain, but that would depend on establishing a reliable oxygen supply to the cave and there being enough of an air pocket left for the boys to survive.

To drill from above to create an escape route. This is a long-term solution and also carries the risk of collapsing the roof of the cave.

Mr Funan, 37, died as he returned from delivering air tanks to the flooded cave where the team has been stranded for two weeks.

The death of such an experienced diver along with news that oxygen

levels in the cave have fallen to 15 per cent – down from a healthy level of 21 per cent – means time is running out. Divers are working furiously to lay more oxygen pipes to the boys' chamber.

The boys, aged 11 to 16, and their coach have been trapped in the flooded cave since June 23.

A huge operation is underway at the Tham Luang Nang Non cave complex, where dozens of Thai Navy SEALs and international experts are attempting to find a way to get the boys out

Divers can only get so far before full diving equipment is required as they must swim though completely submerged passages

The boys entered the huge cavern during fine weather but got stuck when a sudden downpour flooded the tunnels. It is believed they survived by eating huge freshwater snails and drinking dirty water.

The boys are said to be calm, largely due to the steady leadership of their coach. While some of them get diving lessons from Thai Navy experts, the others rest and chatter quietly.

When they were first found, the boys were fed the high-energy glucose gel used by elite sportsmen to rapidly boost their energy levels after so long without food.

Although they have been reintroduced to solid food, it is by necessity all cold, and in their letters to their parents the boys dreamed of fried chicken.

It takes about 11 hours for new pieces of information to reach parents. Experienced divers have to walk on rocky terrain against strong currents and swim and dive in zero visibility through a labyrinth of passages in murky water for six hours to reach the survivors. It then takes them five hours to come back out.

A group of volunteers prepare to leave in search of alternative entry points to the Tham Luang cave area as rescue operation continues for the 12 boys and their football team coach trapped in the cave

Thail soldiers and police officers are seen as rescue operations continue for the 12 boys and their football team coach trapped in Tham Luang cave at Khun Nam Nang Non Forest Park

Thai military personnel inside a cave complex during the ongoing rescue operations for the youth soccer team and their assistant coach, at Tham Luang cave in Khun Nam Nang Non Forest Park

Tham Luang Nang Non means 'the great cave of the sleeping lady'. It is named after a princess who fell in love with a stable boy and became pregnant.

Her father killed the boy and the distraught princess took her own life by stabbing herself in the heart with a hairpin. The water that flows through Tham Luang is said to be her blood.

Since the boys were found, the national park above the cave has turned into something resembling a battle zone, with engineers, soldiers, police and navy rescue divers jostling for space in a makeshift camp.

Last night, a joint letter from the boys' parents was posted on social media, forgiving the coach.

The parents wrote: 'Please don't blame yourself. We want you to know that no parents are angry with you at all so don't you worry about that. Everyone understands and you have all of our support.'

One of the most moving letters from the boys was from 'Tun' (Nattawoot Thakamsai, 14), who put on a brave face to allay his parents' darkest fears: 'I miss you, Mum and Dad, and miss my family. Don't worry about me, I can take care of myself.'

Prajak Sutham's, grandmother of footballer Kiangkham Janthapoon, holds a photo of him with his parents when he was aged 2

Two more Brits to the rescue... in the riskiest cave mission of all

Two more British experts have been drafted in to the international effort to save the boys in what has been described as ‘the most complex rescue mission’ ever attempted in caves.

Cave divers Chris Jewell and Jason Mallinson joined countrymen Rick Stanton, John Volanthen and Vernon Unsworth to add their expertise to the operation in extremely hazardous conditions. The pair left Heathrow with half a ton of cave-diving equipment.

To underline the challenges facing the operation last night, seven rescue workers were hurt when their car went over a steep 70ft bank and overturned.

The team was scouting the mountainside above the Tham Luang caves where the boys are trapped, searching for holes and fissures which might offer an alternative escape route.

Cave divers Chris Jewell (pictured) and Jason Mallinson have been drafted in to the international effort to save the boys in what has been described as ‘the most complex rescue mission’ ever attempted in caves

Jason Mallinson and his colleague brought haf a ton of rescue gear with them from Britain to help with the effort

Like the other divers, they are experts with long track records in similar situations who will lend their expertise in the massive international effort

On Friday, a former Thai navy diver was killed in the tunnels when he ran out of air.

His death only served to underline the fact that extracting the boys through cramped, water-filled tunnels using diving equipment is by far the riskiest option.

Leading British cave diving expert Martyn Farr, 67, said such a plan could be justified only if no other option was open and the boys were in imminent danger.

‘I’ve been a cave diver for 47 years and this is absolutely a last-ditch way to get them out,’ he told The Mail on Sunday from his home in Wales. ‘This is beyond a shadow of a doubt the most complex rescue ever attempted in the caving world.

They will join fellow British divers Rick Stanton (right) and John Volanthen (left), who were the first to reach twelve trapped schoolboy footballers in the waters of the cave system

British cave divers Richard Stanton (left), Robert Harper (centre) and John Volanthen (right) arrive at Khun Nam Nang Non Forest Park near the Tham Luang cave on June 27

‘When these youngsters waded in there, the tunnel was obviously negotiable. They had one torrential downpour and the flooding resulted. If you have a similar level of deluge, it will completely outstrip the ability of any pumping systems.’

Massive industrial pumps have been removing 13,000 litres of water an hour from the two miles of flooded caves and passages separating the boys from safety.

Mr Farr added: ‘In terms of complexity, nothing like this has been done, where you can’t see your hand in front of your face, where there are obstacles all along the route and of course you’re dealing with children who’ve never dived before.’