The football coach trapped in a cave with 12 Thai boys has apologised to their parents in a letter sent out through divers.
Other messages written on pages from a notebook saw the boys send messages of reassurance to their worried relatives.
Rescuers have said they will be forced to try an underwater evacuation if heavy rains return.
In a letter sent out through divers Ekapol Chanthawong, the coach of the Wild Boars football team, wrote: “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 say thanks for all the support and I want to apologise to the parents.”
In letters to their parents, one boy wrote: “I’m doing fine, but the air is a little cold but don’t worry. Although, don’t forget to set up my birthday party.”
Another, named as Tun, wrote: “Mum and Dad, please don’t worry, I am fine. I’ve told Yod to get ready to take me out for fried chicken. With love.”
The rest of the scribbled letters on pages from a notebook sent similar messages, telling parents not to worry and sending love to them.
One boy, Mick, wrote: “Don’t be worried, I miss everyone. Grandpa, uncle, mum, dad, and siblings I love you all. I’m happy being here inside, the navy SEALS have taken good care. Love you all.”
The boys and their coach have been trapped in the cave since June 23 when monsoon flooding cut them off.
Rescuers found them 10 days later and are now working to find a way to get them out.
A former Thai navy SEAL has died during the rescue effort while diving in flooded passageways to deliver oxygen supplies.
The boys have been practising wearing dive masks and breathing in case they have to be brought out underwater, but it has also been suggested that they may have to wait months inside until a safe way out is available.
Authorities are also looking at alternative options like finding a shaft or drilling into the mountain to create the equivalent of a ‘back door’ into the cave.
Billionaire Elon Musk has also said he will help.
Some good feedback from cave experts in Thailand. Iterating with them on an escape pod design that might be safe enough to try. Also building an inflatable tube with airlocks. Less likely to work, given tricky contours, but great if it does.
— Elon Musk (@elonmusk) July 7, 2018
The entrepreneur behind the Tesla automobile and the SpaceX rocket company also owns Boring Co., which digs tunnels for advanced transport systems and has advanced ground-penetrating radar.
After he was approached on Twitter to help the trapped footballers, Mr Musk suggested that an air tunnel constructed with soft tubing like a Bouncy Castle could provide flexible passage out.
He said: “Boring Co has advanced ground penetrating radar & is pretty good at digging holes. Don’t know if pump rate is limited by electric power or pumps are too smal. If so, could dropship fully charged Powerpacks and pumps.”