Days after Boring Company and SpaceX engineers traveled to Thailand to assist in the rescue mission of 12 boys and their soccer coach in a cave in Chiang Rai, Elon Musk has shared images of the “kid-size submarine” his team developed to evacuate the trapped children. However, once the first four of the boys were rescued from the cave, it was uncertain whether the Thai government would employ Musk’s submarine for the next round of evacuations. Musk tweeted images of his submarine prototype, suggesting the submarine is still en route to Thailand.

On June 23, the group of 12 boys between the ages of 11 and 16 and their 25-year-old soccer coach found themselves stuck in a Tham Luang Nang Non cave after exploring the cave system in the Chiang Rai province. Soon after their location was discovered on July 2, Musk shared multiple ideas for the rescue mission on Twitter and later announced that his engineers were en route to assist with the rescue mission. After sharing some of the feedback he had received from the team in Thailand, Musk tweeted that SpaceX engineers were eight hours away from completing the submarine that was capable of rescuing the stranded boys.

Watch divers test Elon Musk’s submarine for the Thai cave rescue mission.

Musk described the new rescue vehicle as “double-layer Kevlar pressure pods with Teflon coating to slip by rocks.” After consulting with people on Twitter, Musk conceded that it would be best to add an air tank to the front of the model and a vent valve to its rear, creating a slow-bleed airflow rate that would allow passengers to breathe without scuba training. This would be helpful in the event of a panic attack, wherein a passenger struggles to self-regulate breathing patterns. The Boring Company CEO said the prototype was tested in a pool with subjects untrained in scuba.

Less than 24 hours after Musk shared these plans, Chiang Rai Governor Narongsak Osottanakorn held a press conference to announce that four of the 12 boys had been successfully evacuated. While the rescue team did consist of 90 divers and engineers from across the globe, Osottanakorn did not specify whether SpaceX and Boring Company engineers played a role and if Musk’s submarine would be deployed for the next phase of evacuations.

However, it’s clear the submarine is still underway. On Sunday, journalist Raveen Aujmaya tweeted a rendering of Musk’s submarine saying that the vessel would be used in the rescue mission. Musk later commented that the drawing was “pretty close” to his model, differing in that his carries a nose cone on the front and openings on the side for hoses to exit. He then shared images that appear to be the submarine ready to ship to Thailand.

Assuming the submarine was completed in the eight-hour deadline Musk stated, the shipment will take 17 hours to arrive in Thailand. At the press conference, Osottanakorn warned that Thailand’s rescue team would need to make sure all conditions were stable before launching the next phase of evacuations and that the next strategy meeting for rescue workers is scheduled for Sunday night.

While this buys Musk some time to ensure his submarine arrives, timing is critical for the remaining boys and their coach. With monsoon season beginning and oxygen levels thinning in the cave system, the situation is still dire.