Elon Musk has revealed a tiny submarine he says can be used to save the Thai boys currently stuck in a cave. The same technology – which is shaped like a small rocket – could be used as an escape pod in emergency space evacuations, the billionaire has claimed. Mr Musk has been trying to come up with solutions to try and save the children as the Thai government works to save them from being stuck underground. Thailand schoolboys rescue - in pictures Show all 21 1 /21 Thailand schoolboys rescue - in pictures Thailand schoolboys rescue - in pictures Police and military personnel use umbrellas to cover a stretcher near a helicopter and an ambulance at a military airport in Chiang Rai as rescue operations continue for those still trapped inside the cave in Khun Nam Nang Non Forest Park in the Mae Sai district. Four boys among the group of 13 trapped in a flooded Thai cave for more than a fortnight were rescued on July 8 after surviving a treacherous escape, raising hopes elite divers would also save the others soon. AFP/Getty Thailand schoolboys rescue - in pictures Thai rescue team members walk inside the cave Rex Features Thailand schoolboys rescue - in pictures An ambulance exits from the Tham Luang cave area AFP/Getty Images Thailand schoolboys rescue - in pictures A military helicopter carrying rescued schoolboys approaches to land at a military airport in Chiang Rai REUTERS Thailand schoolboys rescue - in pictures Rescuers hands locked with a caption reading "We Thai and the international teams join forces to bring the young Wild Boars home" where 12 boys and their soccer coach have been trapped since June 23 in a cave in Mae Sai, Chiang Rai province, northern Thailand. The operation has begun to rescue 12 boys and their soccer coach who will need to dive out of the flooded Thai cave where they have been trapped for more than two weeks, with officials saying Sunday morning that "today is D-Day. AP Thailand schoolboys rescue - in pictures A Thai policeman stands guard at an entrance of the cave as rescue operations continue for 12 boys and their coach trapped at Tham Luang cave at Khun Nam Nang Non Forest Park in the Mae Sai district of Chiang Rai province on early July 8, 2018. Thai authorities told media on July 8 to leave a camp site near the cave where 12 boys and their coach have been trapped for more than two weeks so that "victims" could be helped, possibly signalling a long-awaited rescue effort to get them out. AFP/Getty Images Thailand schoolboys rescue - in pictures Rescuers are seen drillining ahead of the operation at the Tham Luang cave complex, where 12 boys and their soccer coach are trapped, in the northern province of Chiang Rai, Thailand REUTERS Thailand schoolboys rescue - in pictures Rescuers are seen drillining ahead of the operation at the Tham Luang cave complex, where 12 boys and their soccer coach are trapped, in the northern province of Chiang Rai, Thailand REUTERS Thailand schoolboys rescue - in pictures Ruamkatanyu Foundation rescuers are seen drillining ahead of the operation at the Tham Luang cave complex, where 12 boys and their soccer coach are trapped, in the northern province of Chiang Rai, Thailand REUTERS Thailand schoolboys rescue - in pictures Thai policemen stand guard near a cave where 12 boys and their soccer coach have been trapped since June 23, in Mae Sai, Chiang Rai province, in northern Thailand Sunday, July 8, 2018. Thai authorities are racing to pump out water from the flooded cave before more rains are forecast to hit the northern region. AP Thailand schoolboys rescue - in pictures Journalists clear and prepare to leave the cave area during the 'D-Day' for the ongoing rescue operation for the child soccer team and their assistant coach to exit the cave at Tham Luang cave in Khun Nam Nang Non Forest Park, Chiang Rai province, Thailand, 08 July 2018. The officials' operations are underway to safely bring out the 13 members of the youth soccer team including their assistant coach who have been trapped in Tham Luang cave since 23 June 2018, out of the cave according to former Chiang Rai Governor Narongsak Osottanakorn said. EPA Thailand schoolboys rescue - in pictures Thai family members of missing football players and their coach (R) pass to meet with the officers during rescue operations to save a soccer team at Tham Luang cave in Khun Nam Nang Non Forest Park, Chiang Rai province, Thailand, 03 July 2018. According to Chiang Rai provincial Governor Narongsak Osatanakorn rescuers are taking supplies and food into the cave to sustain the team while there extraction is worked out. EPA Thailand schoolboys rescue - in pictures Rescuer walk out from cave where 12 boys and their soccer coach have been trapped since June 23, in Mae Sai, Chiang Rai province, in northern Thailand Sunday, July 8, 2018. Thai authorities are racing to pump out water from the flooded cave before more rains are forecast to hit the northern region. AP Thailand schoolboys rescue - in pictures Policeman line up on the main road leading to Tham Luang Nang Non cave on July 8, 2018 in Chiang Rai, Thailand. Divers began an effort to pull the 12 boys and their soccer coach on Sunday morning after they were found alive in the cave at northern Thailand. Videos released by the Thai Navy SEAL shows the boys, aged 11 to 16, and their 25-year-old coach are in good health in Tham Luang Nang Non cave and the challenge now will be to extract the party safely. Getty Images Thailand schoolboys rescue - in pictures Rescue workers along the main road leading to Tham Luang Nang Non cave as the first 2 ambulances carrying 2 boys pass by on July 8, 2018 in Chiang Rai, Thailand. Divers began an effort to pull the 12 boys and their soccer coach on Sunday morning after they were found alive in the cave at northern Thailand.<doc-sep>Scuba divers in Thailand have already rescued four of the 12 boys who have been stranded, along with their coach, in a flooded cave. And they are hoping to rescue the rest in the next couple of days. But in the meantime, Elon Musk has continued working on alternative strategies divers could use if conventional diving proves too difficult for the remaining boys. On Saturday, Musk settled on the idea of building "a tiny, kid-size submarine using the liquid oxygen transfer tube of Falcon rocket as hull." He ordered SpaceX engineers to begin building the device, saying that it could be ready by the end of the day on Saturday. Elon Musk / SpaceX Elon Musk / SpaceX By the time it was finished, Thai officials had already begun their rescue operation without Musk's help, so the technology likely won't be needed. But Musk decided to press forward anyway, tweeting that "even if not useful here, perhaps it will be in a future situation." Advertisement On Sunday, he posted photos of the completed device. "Testing for 3 more hours in LA, then it’s on a plane to Thailand," Musk tweeted late on Sunday morning, California time. Musk also posted a video of the device being tested in a Los Angeles pool: Testing underwater in LA pool pic.twitter.com/CDO2mtjP2D — Elon Musk (@elonmusk) July 8, 2018 Update: The tube is really narrow. Some diagrams online show one passageway narrowing to as little as 38 cm—about 15 inches—at its tightest point. We asked Musk if the cylinder would really fit through such a small space, and he responded on Twitter that the cylinder was 31 cm wide—just over a foot. That would obviously be too narrow for many adults to squeeze into, but perhaps it's just big enough for the Thai teenagers—especially the younger ones—to get in.<doc-sep>See more You guys, Elon Musk has a plan to rescue the Thai boys who are, as we speak, undertaking a risky dive out of a pitch-black, narrow labyrinth of caves swirling with rushing water. Musk's solution to this dangerous situation? A tiny, kid-size submarine — in photos it looks like a glorified metal cylinder just big enough to cram a child inside — that SpaceX engineers built in a day. What could go wrong? Right now, eight members of the soccer team have already been rescued, so any of the boys who were even slightly tempted to try this invention will likely be disappointed. But assuming the current rescue plan was a no-go: Would this sub make any sense for such a risky rescue? "My hat is off to him for doing this," said Richard Black, a cave diver and instructor with the Florida Dive Connection, a board member on the ADM Exploration Foundation in Florida, and a team diver with Karst Underwater Research. But "I think it's impractical," Black said. "Technology fails, and this is essentially a new item, a new product that is untested." To offer some perspective, cave-diving equipment and safety protocols being used by the current rescue operation have been refined, troubleshooted and tested in tens of thousands of different cave-diving environments and over decades. Twitter rescue The entrepreneur and inventor has been throwing out several ideas for the rescue on Twitter, including an inflatable tube with airlocks, before settling on a plan he described on Saturday (July 7) on Twitter. "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," Musk tweeted. See more Less than 24 hours later, Must tweeted a video of the prototype mini-submarine being tested in a Los Angeles pool, along with photos of the completed device, which basically looks like a very large metal pipe fitted with clear caps at the front and back, oxygen hoses and a nose cone in the front to protect against rocks. And that, apparently, was enough testing for Musk to deem it ready. "Testing for 3 more hours in LA, then it’s on a plane to Thailand," Musk tweeted late night on Sunday (July 8) California time. See more Dangerous, unpredictable environment While the idea could potentially work in some caves, it might not work in others, George Veni, executive director of the National Cave and Karst Research Institute and president of the International Union of Speleology, told Live Science in an email. "There is also the question of how long the air supply will last, assuring the tube will be airtight despite the inevitable bumps and bangs it will experience, will it have an independent regulator to breathe through if it does leak so the child doesn’t drown in it," Veni said. Black agreed. Although the submarine may technically be small enough to fit through the smallest reported constriction or tightest spot, "there's no visibility, there's muddy water, and the water is flowing," Black told Live Science. "If they were not to bring this capsule in at exactly the right angle, there's the potential that it could become lodged in there." At that point, they would have to spend precious minutes — and oxygen — trying to get it unstuck, Black. What's more, this capsule is incredibly small — one report says about 12 inches (31 centimeters) — in diameter. "I'm a cave diver and I can't imagine being put into this," Black said. "If the kids were to panic or if there were some failure you would have absolutely no recourse; you couldn't open it." And again, with no visibility, the divers might not even know something was wrong inside the capsule. And then there is the fact that divers would have to carry this thing and much of this route is dry, Black said. "You have to carry the capsule overland and then put the kid back into it," Black said. "Water has a way of finding its way into sealed compartments," so every time they sealed and unsealed the submarine, there's a chance to cause water to leak in, or oxygen to leak out, he said. There are a few situations where such a device might be useful, Black said. If anyone was incapacitated or simply too panicked to breathe underwater, this capsule might be a good approach. Althugh the odds of this kiddie sub being used in the current rescue are dwindling by the hour, Musk said he will continue to develop the technology for other applications. Originally published on Live Science.<doc-sep>Elon Musk has a plan. The billionaire entrepreneur and engineers at his private spaceflight company SpaceX designed a “kid-size submarine” that they said could help with a harrowing rescue operation underway to retrieve a group of boys trapped in a flooded cave in Thailand. It arrived on Monday night, and the mogul shared some thoughts and photos on his Twitter account: Just returned from Cave 3. Mini-sub is ready if needed. It is made of rocket parts & named Wild Boar after kids’ soccer team. Leaving here in case it may be useful in the future. Thailand is so beautiful. pic.twitter.com/EHNh8ydaTT — Elon Musk (@elonmusk) July 9, 2018 Earlier on Monday, Musk shared photos and videos of the rescue pod on Twitter, including footage of engineers testing the device in a pool in Los Angeles and maneuvering the metallic pod through a simulated narrow passageway underwater. Simulating maneuvering through a narrow passage pic.twitter.com/2z01Ut3vxJ — Elon Musk (@elonmusk) July 9, 2018 Musk said the team is working on a second, shorter version. “Mini-sub arriving in about 17 hours,” he tweeted Sunday. “Hopefully useful. If not, perhaps it will be in a future situation.” So far, eight members of a youth soccer team have been rescued after being trapped in the cave for more than two weeks. Four other boys on the team and their 25-year-old coach remain in the Tham Luang cave complex, which flooded from heavy monsoon rains and became sealed off. Musk and his team have been in touch with officials in Thailand, a SpaceX spokesperson confirmed, and Musk tweeted Sunday that the sub’s design is based on feedback from dive teams assisting with the rescue operation. The device was fashioned out of a tube for SpaceX’s Falcon 9 rocket. Musk said the sub’s aluminum shell has four ports on the front and rear to connect to oxygen tanks and weighs about 90 pounds. Testing underwater in LA pool pic.twitter.com/CDO2mtjP2D — Elon Musk (@elonmusk) July 8, 2018 “Light enough to be carried by 2 divers, small enough to get through narrow gaps,” Musk tweeted. “Extremely robust.” Musk added that with some modifications, “this could also work as an escape pod in space.” Thai navy SEALs and a team of foreign divers are conducting the rescue operation, and an international team of experts, including a U.S. military team, is providing assistance. FOLLOW NBC NEWS MACH ON TWITTER, FACEBOOK, AND INSTAGRAM.<doc-sep>
An ambulance leaves the Tham Luang cave area after divers evacuated some of the 12 boys and their coach trapped at the cave in Khun Nam Nang Non Forest Park in the Mae Sai district of Chiang Rai province on July 8, 2018. - Elite divers on July 8 began the extremely dangerous operation to extract 12 boys and their football coach who have been trapped in a flooded cave complex in northern Thailand for more than two weeks, as looming monsoon rains threatened the rescue effort. (Photo by LILLIAN SUWANRUMPHA / AFP) / (Photo credit should read LILLIAN SUWANRUMPHA/AFP/Getty Images) 12 boys and their coach all out of Thai cave Some of the boys who were trapped in a cave in Northern Thailand outside a hospital in Chiang Rai after being discharged. CHIANG RAI, THAILAND - JULY 18: Twelve boys and their coach from the "Wild Boars" soccer team arrive for a press conference for the first time since they were rescued from a cave in northern Thailand last week, on July 18, 2018 in Chiang Rai, Thailand. The 12 boys, aged 11 to 16, and their 25-year-old coach were discharged early from Chiang Rai Prachanukroh hospital after a speedy recovery and thanked those involved in their rescue. (Photo by Linh Pham/Getty Images) (CNN) — Billionaire tech entrepreneur Elon Musk shared photos and videos of a metallic pod that may help rescue a group of boys trapped in a cave in Thailand. Footage shared on Musk’s Twitter account shows a group testing the device in a Los Angeles high school swimming pool. Musk said in a tweet Sunday evening that the pod — or “kid-size submarine” — was en route to Thailand and would arrive in about 17 hours. “Hopefully useful,” he said in one tweet. “If not, perhaps it will be in a future situation.” His updates came after US and Thai officials confirmed Sunday that four boys had been rescued from a flooded cave network after spending 15 days trapped along with their soccer team and coach. They were escorted out by a group of Thai and international divers. Eight boys and the coach remain trapped, and the ordeal has been a closely watched news story around the globe. Musk — who runs multiple California-based companies, including SpaceX and Tesla — said Friday that engineers on his staff would travel to Thailand to assess how they might help. He provided sporadic updates on his efforts over the weekend. Musk said based on “feedback from Thailand,” the engineers decided to build a “tiny, kid-size submarine” using a large silver tube meant to be affixed to a SpaceX Falcon 9 rocket. Musk explained the metal tube would be “[l]ight enough to be carried by 2 divers, small enough to get through narrow gaps” in the cave, and “extremely robust.” The device is also outfitted with oxygen ports and a nose cone to protect it from impact with rocks, according to Musk’s tweets. In one of the videos of testing that Musk shared, a man is seen emerging from the roughly 6-foot long metallic cylinder. There’s been no shortage of warnings in recent days about how risky the rescue attempt is – not least the death of former Thai Navy Sgt. Saman Kunan, an ex-SEAL, who died early Friday morning due to a lack of air while attempting to return to a command center deep underground. As of early Monday morning local time, rescue efforts were suspended in Thailand as teams restocked supplies and prepared to get the rest of the team out of the cave. CNN’s Jonathan Miller reported that the eight boys and coach who remain stranded in the cave would likely have to stay put for a couple of days due to issues restocking oxygen supplies. Meanwhile, rescuers have a dwindling window of opportunity, with forecasters predicting the return of heavy monsoon rains in the coming days, effectively sealing off the cave until October. CNN’s Brian Ries, Meg Wagner, Euan McKirdy, James Masters and Hilary Whiteman contributed to this report.