Elon Musk's kid-size submarine is headed to Thailand, but rescuers probably won't need it

Mini-sub to the rescue! Or, maybe not.

On Sunday afternoon, Elon Musk tweeted that the kid-size submarine his team had developed to assist with the rescue of Thai boys trapped in a cave was en route to Thailand. He expected it to arrive around 11 p.m. Monday, local time.

But phase two of the rescue is already underway, and may in fact be over by the time the sub arrives.

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Over the weekend, the Thai government successfully rescued four boys who had been trapped in the cave since June 23. With the assistance of divers, they swam out with oxygen tanks, along a 2-mile long rope guiding them out.

The team had to pause rescue efforts as weather conditions worsened and made the narrow cave system more difficult to navigate. But the rains stopped on Monday, and the mission resumed at 11 a.m. local time. So far, divers have rescued four additional boys, which leaves four more and their soccer coach to go.

Officials told Reuters that Monday's rescue operation would take between 10 and 20 hours. Musk expects his submarine to arrive in the middle of that window — about 12 hours into the second phase of the operation. He said that it would hopefully be useful, but, "if not, perhaps it will be in a future situation."

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The New York Times reports that as of current writing, the day's operation was winding down. So the sub still could come into play on a third day of rescues.

Musk shared plans for his kid-size submarine over the weekend, featuring a video demonstration. He initially sprung into action and started communicating with Thai officials and engineers to assist with the rescue at the behest of Twitter users.

Whether the sub proves useful or not, at least Elon's considerable hands are on deck.