By David Dixon

Copyright bbc

The Carbis Bay Crew are careful not to reveal where they access the old mine workings, to prevent other less-qualified people following in their footsteps.

Crew member Patrick Moret said: “It’s a very, very dangerous hobby, most of the guys have some qualification that is relevant, we’ve got three people that actually train rope access and rope rescue in the group.

“No-one goes underground unless they have had a good thrashing in the training.”

The film focuses on the benefits to mental health for the group and is supported by charity MANUP? which promotes “real, impactful action on helping men’s mental health”.

In the film, Mr Moret talked about the importance of a shared mission for men these days.

“They’ll go hunting together, they’ll go out on a boat together, they go to war together and I think it’s a need to feel part of something,” he said.

“If people are struggling at work or in marital life it’s a great outlet.”