Far beneath the waves off the coast of the Bahamas lies the Black Hole of Andros and it does not sound like a lot of fun.

Paul Rose says: "There's a layer of bacterial matter 18m down, it's incredibly oily and, as you enter, you lose all visibility. It's unusual to smell anything underwater but, because your skin absorbs it, you can smell it – like rotten eggs. It's also baking hot, about 35ºC, and you get quite disorientated."

Paul is a former vice president of the Royal Geographical Society, the base commander of the British Antarctic Survey base and is now the presenter of Oceans, an eight-parts series that covers maritime archaeology, biology, conservation, history and culture.

A breezy east Londoner, who began diving in 1969, Paul ventured into the black hole in search of evidence about how the oceans work. Located in the part of the Atlantic Ocean from which the Gulf Stream springs, it offers an insight into a past world – a snapshot of what the oceans were like three-and-a-half billion years ago. "I've really wanted to present a series about great diving expeditions with great settings," he says. "I've always been inspired by slightly-old fashioned films, along the lines of the programmes that first inspired me to dive, like the great Jacques Cousteau expeditions and the adventure series Sea Hunt."

Oceans employs the latest diving and high-definition broadcasting technology to capture stunning footage. "We're backed by crews with a lot of experience with the BBC's Natural History Unit." says Paul. "The cameras were so good that, when you got back, you'd see things in playback you hadn't actually seen with your own eyes."

The four-strong presenting team aims to explain much about the seas and what they may become, with a historical and cultural perspective provided by Lucy Blue from the University of Southampton. "The oceans aren't just about the natural history," Lucy says. "They are impacted on as much by human action as by animals."

The result of such interaction is examined by conservation expert Philippe Cousteau, grandson of Jacques. "We wanted something not only exciting to watch but carrying a strong message," says Philippe. "The oceans are not just this vast empty space, but are critical to our lives – they regulate our climate, provide oxygen and food to so many people, they serve vital functions for us to exist on this planet. But they are changing – and not for the better."

The oceans contain more than 99 per cent of living space on Earth and up to 10m species live in the deep sea alone. Evidence of the changes to them is widespread. In Baja, for example, the Humboldt squid population has exploded as a result of environmental change.

"You see changes like that all over the world," says Philippe.

"We're also seeing shark populations in decline and, if you remove them, the entire system becomes unbalanced. Oceans wants to show an appreciation of how wonderful and incredible this world is, and hopefully inspire people to realise what we've got to lose."

One of the most amazing scenes came late into Paul Rose's final dive. He tied a six-pound chunk of tuna to his weight belt, hoping to attract a six-gill shark.

"I was almost out of time when I saw these two green eyes," he explains, still breathless with the excitement. "Here
we were with a creature that has been
in existence for 200 million years... absolutely fantastic."