Elon Muskhas built a prototype submarine to help aid the rescue of a group of 12 children and their football coach trapped in a cave in Thailand.

The billionaire entrepreneur shared that he is working with cave experts in Thailand to produce an escape pod design to free the trapped group “that might be safe enough to try”. The pod, described as a “tiny, kid-sized submarine”, is light enough to be carried by two divers and is small enough to fit through narrow gaps.

Musk’s team used the liquid oxygen transfer tube of SpaceX's Falcon rocket as a hull for the mini-submarine. In a series of videos on his Twitter account, Musk shares the tests that his team performed in a high school swimming pool in Los Angeles.

Musk showed divers navigating through metal poles in a swimming pool to simulate the tight spaces in the caves in Thailand. In one short clip, the team emerged from the water, opening the submarine to reveal a team member inside.

Heavy monsoon rains meant that the Thai government had to accelerate its rescue operation to extract the children on Sunday, meaning that this pod will not be used to rescue this team. On Twitter, Musk said: "Extremely talented dive team. Makes sense given monsoon. Godspeed."