The project would take "about 8 hours" to build, Musk added, or less than half the 17 hours it would take to fly it to Thailand.

It's not certain that the Thai government is committed to using the mini sub, and there's still plenty of risk in navigating between rocks and other hazards. Not that officials may have other options. Some of the children don't know how to swim, and those that did would still face a perilous journey. And with heavy rain coming in the days ahead, the team might not have the option of waiting it out. The submarine would be relatively safe, even if it didn't get rigorous testing before entering service.