• Elon Musk on Sunday posted multiple videos on Twitter of what he has described as a “kid-sized submarine” being tested underwater.
  • Musk said it could help rescue the youth soccer team trapped in a cave in Thailand.
  • Engineers from SpaceX and The Boring Company are in Thailand assisting the government’s rescue mission, Musk has said.

Elon Musk is testing equipment designed to help rescue the remaining members of a Thai youth soccer team trapped in a cave, the Tesla CEO tweeted on Sunday.

Hours after four boys were confirmed to have been rescued from the cave, Musk tweeted videos of a small submarine-like vessel being tested in a swimming pool and said he was sending it to Thailand.

Last week, Musk offered engineers from two of his other companies, SpaceX and The Boring Company, to assist the Thai government.

A video Musk tweeted on Sunday shows three people in scuba gear pushing and pulling the tube across a pool.

https://twitter.com/elonmusk/status/1016029967270928384?ref_src=twsrc%5Etfw

Another video shows the submarine being lifted out of the pool and a person popping out of the submarine completely dry.

Another shows the submarine underwater for 35 seconds.

https://twitter.com/elonmusk/status/1016060413476143104?ref_src=twsrc%5Etfw

Sam Teller, a Boring Company representative, told The Associated Press that four company engineers were "offering support in any way the government deems useful."

Here's another look at the vessel:

https://twitter.com/elonmusk/status/1016000972730978304?ref_src=twsrc%5Etfw

Musk first tweeted about the boys trapped in the cave on Wednesday after somebody asked him whether he would assist. He said he would be "happy to help if there is a way to do so."

Musk then started brainstorming ideas on Twitter to help.

On Friday, he tweeted: "SpaceX & Boring Co engineers headed to Thailand tomorrow to see if we can be helpful to govt."

In one tweet, he suggested a tube or series of tubes be sent through the cave network and inflated, creating a tunnel for the team to travel through without needing to scuba dive.

On Saturday, Musk tweeted that he was interested in designing "a tiny, kid-size submarine" that would be "light enough to be carried by 2 divers, small enough to get through narrow gaps."

In later tweets, Musk said the submarine he was working on has four handles in the front and four in the rear, along with four air-tank connections. He also said the device could maneuver through the narrowest passages.

As of Sunday, eight members of the soccer team, ages 11 to 16, and their 25-year-old coach remained trapped in the cave. Officials have said the rescue could take four days to complete. The team has been trapped in the cave for two weeks.