David Attenborough has shared the 'biggest message he's ever told' as he celebrates 99th birthday

Sir David Attenborough's latest film contains the 'biggest message he's ever told' as the veteran broadcaster celebrates his 99th birthday.

The first screening of Ocean With David Attenborough took place at the Southbank Centre in London on Tuesday (6 May).

In the film, Attenborough draws on a lifetime of knowledge to explain why ocean recovery is vital for a healthy future.

"After almost 100 years on the planet, I now understand the most important place on Earth is not on land, but at sea," the presenter said.

Promising to be 'very different' to his other projects, one of the directors of Ocean said: "Nothing has come close to how important this film is."

Toby Nowlan told Sky News: "I remember sitting on a very cold beach off Sussex, filming with him, and we were doing the opening and closing words for the film.

"It was such a poignant moment. They were the most powerful words I've ever heard him say.

"And if we save the ocean, we save our world. It really hit me and, yeah, I welled up."

Nowlan added that the documentary was 'the biggest message he's ever told', and explained why it should be taken as a positive message.

Sir David Attenborough's new film highlights the important environmental role of oceans (Altitude Films)

"There's been a lot of doom and gloom over the last few years - we want the take home to be: if we save our ocean, we can make a huge difference for our climate, for our fisheries, for conservation, for food security," he said.

Keith Scholey, another director, recalled what it was like working with Attenborough back in the 80s.

"I've had this privilege all my career of working with the great man," he explained.

It promises to be 'very different' to his other projects (Altitude Films)

"He is a huge team worker. He does what he does incredibly well, he expects very high standards, but it's always been a really fun process working with him."

Opening up about his incredible work ethic, Scholey stated that 'the man never stops'.

"And I think for him, time is very precious and you never waste time. He certainly never wastes time. And that's infectious to all the people who work with him," he added.

Attenborough has drawn on a lifetime of knowledge (Altitude Films)

"I'm sure this isn't his last documentary at all, and in fact I know there are other things happening, but I think this is a really important one."

In the film, Sir David was hopeful about the future, and said: “The ocean can recover faster than we thought possible.

“If we just let nature take its course, the sea will save itself.

“If we save the sea, we save our world.”

Ocean With David Attenborough is set to land on National Geographic, Disney+ and Hulu later this year.