One of the British divers who helped rescue the Thai soccer team just confirmed what many suspected about Elon Musk's somewhat bizarre attempt at helping: It was never going to work.

In an interview with CNN, British diver Vern Unsworth called Musk's submarine "just a PR stunt" that "had absolutely no chance of working."

SEE ALSO: Thai cave rescue saga shows how Elon Musk's narcissism gets the best of him

Unsworth, who according to CNN played a "pivotal" role in the rescue, appeared exasperated when asked about Musk.

"He can stick his submarine where it hurts," he said. "It just had absolutely no chance of working. He had no conception of what the cave passage was like. "

The Tesla and SpaceX CEO caused a stir on social media last week, when he essentially live-tweeted his plans to aid with the massive rescue effort. That plan culminated with a kid-sized submarine, which Musk himself delivered to officials in Thailand.

Musk being Musk, the billionaire didn't react well when media outlets began reporting one rescue official's remarks, who described the submarine as "not practical." He unleashed one of his famed Twitter rants, saying, "based on extensive cave video review & discussion with several divers who know journey, SpaceX engineering is absolutely certain that mini-sub can do entire journey & demonstrate at any time."

Unsworth, a local cave expert who was one of the first on the scene, shot that notion down. He said the Musk-designed metal tube was far too big and inflexible to make it around the narrow passages of the cave. "It wouldn't have made the first 50 meters into the cave," he said.

When the interviewer pointed out that Musk did actually make it into the cave at one point, Unsworth simply shrugged and replied that the Tesla CEO "was asked to leave very quickly."

Ouch.