The mini sub idea had no credibility. It wasn’t that it would be difficult to get it through, it was impossible. The cave had several restrictions that a body sized sub could not fit through

There was no one in the world better suited to get those kids out than Dr. Richard Harris, and he did exactly that with the help of dozens of other rescuers

Harris is an anesthesiologist who happens to be a world class cave diver with a deep knowledge on dive physiology. He later went on to do some groundbreaking work using hydrogen and oxygen mixtures for deep diving