Just days after engineers from SpaceX and the Boring Company traveled to Thailand to assist with the rescue of a soccer team trapped in the Tham Luang cave complex, CEO Elon Musk says that they are working on a “tiny, kid-size submarine” constructed out of parts from a Falcon 9 rocket. However, it doesn’t appear that the device will be used to rescue the team, as the Thai government launched rescue operations early this morning.

Earlier this week, Musk noted that they were considering a couple of options, from drilling holes into the cave, to constructing an inflatable tube, to some kind of Kevlar escape pod. Since then, he says that their “primary path” is a submarine constructed out of a liquid oxygen transfer tube as a hull, which would be small enough to fit into the cave, but also light enough to be carried to the trapped children by divers.

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. — Elon Musk (@elonmusk) July 7, 2018

Musk replied to questions from Twitter users, saying that the vehicle is “fitted for a kid or small adult to minimize open air,” with compartments to add weights to account for buoyancy. He also noted that the pod has handles on the front and rear, as well as tank connectors to attach up to four tanks. In followup tweets this afternoon, Musk explained that the SpaceX team is currently working on the vehicle, and that he anticipates that it would be complete in eight hours, before being flown to Thailand. A spokesperson from SpaceX declined to comment on the record, but a Boring Company spokesman confirmed that engineers from SpaceX, Tesla, and the Boring Company were working to design, build, and test pods at SpaceX, while other engineers were in Thailand or were on their way, where they’ll continue to coordinate with the Thai government to best figure out how to proceed.

On Sunday, Musk posted a short video and images of the vehicle:

Testing underwater in LA pool pic.twitter.com/CDO2mtjP2D — Elon Musk (@elonmusk) July 8, 2018

The 12 boys and their coach were discovered alive by rescue divers last week after they were trapped by floodwaters in the caves in late June. While the members of the team are currently safe, they’re in a dangerous situation. Oxygen in the cave has since become depleted, and Navy divers have to make a perilous, six-hour dive to reach chamber where they’re trapped. Already, one diver, Petty Officer Saman Gunan of the Royal Thai Navy, died on Thursday. There had been hope that the team might be able to wait out the floodwaters, but the coming rainy season has also lead to discussions that the children, not all of whom can swim, should be brought out one by one by divers.

Musk’s vehicle seems to bypass that potentially-hazardous plan by hauling each child out in a pod, potentially eliminating the need to give the soccer players a crash course in diving. But last night, Thai authorities decided to move forward with rescue operations, sending divers in to extract the children one by one before floodwaters rose any higher. Thus far, four team members have reportedly been saved. As such, Musk indicated on Twitter that they’ll continue to build and test their vehicle, which he indicated could be useful in the future. On Sunday afternoon, he noted that they were still planning to ship the capsule to Thailand.

Updated July 8th 9:30 AM ET: Updated to include statements from Boring Company, as well as updates on the rescue and Musk’s plans.

Updated July 8th 4:20 AM ET: Updated to include Musk’s pictures of the vehicle during testing.