David Attenborough came close to drowning due to faulty 1950s scuba diving equipment

Sir David Attenborough has revealed that he almost drowned when testing a scuba-diving outfit in the Great Barrier Reef in 1957.

The broadcasting veteran and environmentalist was recorded speaking to Prince William at the Royal Festival Hall in May about his new documentary, Ocean. During the event, he was presented with an original version of an open-circuit scuba helmet, popularised by the French oceanographer Jacques-Yves Cousteau.

Nostalgically, he tried on the helmet over his head. “Don’t do that, David. You won’t get it off,” laughed the Prince of Wales. “It’s certainly a strange thing to do,” remarked Attenborough, who turned 99 in May.

After successfully removing the helmet, Attenborough shared the worrying experience he encountered when he first tried on that particular type of helmet. “When I put mine on for the first time, I suddenly felt water coming around [my chin and up over my mouth],” he explained.

“I thought, ‘This can’t be right’. And by the time [the water rose to my nose], I thought, ‘I’m sure this is not right’. But then, of course, if you got this thing screwed on top of you, you can’t breathe,” he added. “You can’t even make yourself heard, you know: ‘Get it off me!’”

To make matters worse, the director who was working on the documentary refused to believe that the equipment was faulty and decided to test it for himself. “So he put it on and I’m happy to say he went under the water and came up even quicker than I did, because there was actually a fault,” Attenborough said.

Attenborough’s new documentary focuses on “wonderful discoveries” made by scientists and explorers over the past 100 years, and looks at “why our ocean is in such poor health, and, perhaps most importantly, shows how it can be restored to health”.

It features oceans across the Americas, Europe, Africa and Oceania and demonstrates methods used to reverse harmful human activity along coral reefs, mangroves, coastal communities, fish farms, marine sanctuaries and other habitats.

Ocean is the latest in a long line of nature documentaries narrated by Attenborough, whose screen career spans seven decades. He first started working at the BBC in the 1950s, hosting wildlife show Zoo Quest, but released his first nature series, Life on Earth, in 1979.

In the last 25 years, Attenborough has released Planet Earth, The Blue Planet and Dynasties, which focused on vulnerable and endangered animal species fighting for survival.

Ocean: With David Attenborough can still be watched in cinemas and is also now available on National Geographic, Disney+ and Hulu.