July 7 (UPI) -- Elon Musk on Saturday said SpaceX engineers are hours away from finishing a "tiny kid-sized submarine" that could be used to extract a soccer team trapped inside a Thailand cave.
The 12 boys and their coach had gone into the cave on an excursion after a soccer game on June 23 and became stranded by heavy rains and flooding.
Via Twitter, Musk has been updating progress on finding a solution.
"Got more great feedback from Thailand. Primary path is basically a tiny, kid-size submarine using the liquid oxygen transfer tube of Falcon rocket as hull. Light enough to be carried by 2 divers, small enough to get through narrow gaps. Extremely robust," he tweeted Saturday.
Musk said the construction will be "complete in about 8 hours, then 17-hour flight to Thailand."
On Saturday, the boys sent notes to their parents through divers. The hand-written letters from the boys soccer team, ages 11-16, were filled with love and hope.
NBC News reported food supplies for the youth soccer team accompanied by one adult include mostly high-calorie gels, so some boys letters showed a desire for tastier food in their letters home.
The youngest boy, Tun, 11, wrote, "Mom and Dad, please don't worry, I am fine ... Get ready to take me out for fried chicken. With love."
"I'm fine, but it's a little bit cold, don't worry and don't forget my birthday," one boy wrote.
Navy divers found the 12 boys and one adult, 25-year-old coach, Ekaphol "Ake" Chantawong, were alive Monday after a nine-day search in the Tham Luang cave complex in Chiang Rai.
The team had gone into the cave on an excursion after a soccer game on June 23 and became stranded by heavy rains and flooding.
The coach, who has faced criticism for taking the boys out in the cave, also wrote an apology note addressed to his players' parents.
"To all the parents, all the kids are still fine. I promise to take the very best care of the kids," The Guardian reported Chantawong wrote in his letter. "I want to say thanks for all the support and I want to apologize to the parents."
Rescuers have to dive through flooded tunnels for six hours to reach the team and it takes another five hours to return to the entrance, CNN reported.
The danger became more apparent when a former naval diver died Friday while placing air tanks in the cave.
The former Thailand Navy SEAL, Saman Kunan, died from lack of oxygen while attempting to return to a command center located a mile inside the cave, government officials said.
Earlier this week, officials said it could take months to get the team out of the deep cavern because floodwaters have blocked the exit. And rescuers said the boys may have to scuba dive to get out.
Chiang Rai Gov. Narongsak Osot-tanakorn, who commands the rescue operation, said at an overnight news conference that the boys who are being trained to swim "cannot dive at this time" and added rescuers mustmove quickly because "we cannot wait until the rain," which may come in days. Rescuers are also looking at alternatively drilling down and hoisting the team out of the cave, but the governor said that would be extremely difficult.