The 12 boys and their coach were trapped for over two weeks in the cave before the Thai Navy SEALs and a group of divers rescued them. Musk first made an attempt to help them himself, though, by sending SpaceX and Boring Company engineers. The team built a mini submarine dubbed "Wild Boar" (after the name of the team), which they believed could transport the boys to safety. However, it seems their efforts were not appreciated.
British diver Caver Vern Unsworth, who helped find the boys, told CNN that the submarine "just had absolutely no chance of working." He elaborated that Musk "had no conception of what the cave passage was like. The submarine, I believe, was about 5-foot-6 long, rigid, so it wouldn’t have gone around corners, gone around any obstacles. It wouldn’t have made it the first 50 meters into the cave from the dive start point."
He also doubted Musk's sincerity, calling the rescue efforts "just a PR stunt" and adding, "He can stick his submarine where it hurts."
Another one of the divers who helped rescue the boys, Australian diver Craig Challen, told ABC.net.au that he didn't know if everyone would make it out alive. "We thought there was a very real prospect that we would be doing body recoveries, rather than live patient extractions from there," he said. "I think everybody is unreservedly pretty happy now."