Despite living on a planet that is two-thirds covered by water, even today we still know more about the surface of Mars than we do about what is going on under the surface of our own oceans.

Over a decade after the first series graced our screens, Blue Planet II returns to give us just a small snapshot of what lies beneath the waves. The breath-taking documentary takes us on a whirlwind tour from the frigid polar seas of the north to the ethereal brine lakes of the deep. But there are moments here that are tinged with sadness.

“The nearest I came to tears when narrating the entire series is when you see those shots of the Great Barrier Reef,” recounts David Attenborough, who returns to the helm to narrate the new series, and has chatted to IFLScience. With the past few years testing the largest living structure to breaking point as sea surface temperatures creep up, the future of the reef balances on a precipice.

“If you’ve ever swum on the Barrier Reef, if you’ve ever seen the glories, the multicoloured variety, the astonishments of a flourishing Barrier Reef which is one of the most beautiful, thrilling, mysterious sights that the world has to offer; if you’ve ever experienced that, and you now look at this desert of white, crumbling, dead coral and think of what was once there, that’s something that brings tears to the eyes,” Attenborough laments.

Over the past 20 years, Attenborough’s documentaries have taken on an increasingly political overtone, aimed at highlighting the impact that threats such as man-made climate change and the ever-burgeoning global population are having on the natural world. And they have a real impact.

Blue Planet II has already been sold to 30 different countries before the series has even finished airing, and Attenborough believes that the inherent secret to the success of his programmes is that natural history documentaries have the ability to draw people from across the age spectrum.

 

“It’s the beauty of it,” he tells us. “Usually I get 10-20 letters a day and during this series that will probably go up to 40. But the astonishing thing is the range of people who write.” From seven-year-old children asking him about dinosaurs to professors of economics quizzing him about the finer details, “that just shows you the breadth of the appeal.”

It’s now 65 years since a bright-eyed 26-year-old David Attenborough first appeared on our television screens with a brief 10-minute programme about the discovery of a prehistoric fish off the coast of Africa.

That was December 1952 and Attenborough had been working at the BBC for just two months, albeit as a junior producer as the head of factual broadcasting at the time thought his teeth were too big to make the grade as a presenter.

But then the coelacanth became headline news. Not only had it previously been thought to have gone extinct with the dinosaurs some 65 million years earlier, but the discovery had sparked tension between the French and South African governments, with France claiming that the African fishermen had caught the creature in its waters.

“I was told that given my university education as a biologist, it was my responsibility to put on and present a programme in the next week to explain to the public what all the fuss was about,” he recollects. “Ten to fifteen minutes they said.”

“And from there I’ve gone on to work for the BBC all my life.”

 

The latest offering from Attenborough has already proven to be a smash hit, with the opening episode of Blue Planet II attracting over 14 million viewers in the UK alone, and it’s not even finished its run yet. Now 91, Attenborough is narrating the 7-part exploration of the world’s oceans, filling Sunday nights with a veritable smorgasbord of natural wonders never before filmed.

From giant trevallies leaping clean from the water to take down fledgling terns, to the aesthetically awkward sex-changing Kobudai wrasse off the Japanese coast, or the icy descent 1,000 meters down to the seafloor of Antarctica, there are plenty of astonishing moments to catch.

After over half a century in the wildlife documentary business, you might think that Attenborough would be hard to impress, but it seems that the BBC Natural History Unit has managed it again.

“The trevally footage was extraordinary,” he says, leaning forward in his chair, the enthusiasm palpable. “These are big fish and when you think of what that involves, you’re swimming underwater and you’ve got to look through the surface, see the bird, and make a calculated judgement of how fast it’s going and where it’s going to be by the time you [jump] out of the water to catch it. It’s quite remarkable behaviour.”

But he doesn’t stop there. “There’s more,” Attenborough gushes. “You’ll see a wonderful fish that actually lays its eggs out of water, and actually likes to live out of water.” He’s now on a roll. “And more than anything, you find that the sea is much more of a complex society than one would imagine with all kinds of communications.” Barely catching his breath, he continues, “you’ll see cuttlefish that tell lies to bigger cuttlefish. Octopuses and coral groupers working together.”

“You really learn that fish are individuals.”

 

But along with all these moments that have never been seen before, comes a serious warning about what we are losing before we even get the chance to see it as we continue to trash the oceans.

It’s not hard to hear the anger behind Attenborough’s words, anger which is also directed towards the current and previous US presidents. He becomes particularly animated when discussing Donald Trump’s ongoing plans to withdraw the US from the 2015 Paris climate agreement, but admits he was equally frustrated for many years by a perceived lack of action from Barack Obama. That changed two years ago in France.

“I was at the climate talks in Paris 18 months ago, Obama had backed it, and I came out thinking that for the first time ever in history, human beings from around the globe have agreed to do something to change their habits, and you thought we were getting somewhere,” Attenborough says. When it comes to the United States’ stance now as the only nation on the planet not signed up, he remains ever hopeful.

“Perhaps this is me just clutching at straws but 30 years ago I felt we were voices crying in the wilderness trying to persuade people that they have a responsibility to the planet,” Attenborough tells us. “But in recent years I feel there’s been a tidal change of opinion, particularly in young people being conscious of their responsibility to the natural world. And that’s very comforting.”

Yet even this comes with a caveat: “The trouble is, the problem is now bigger than it was 30 years ago because we haven’t done anything about it for so long.”

Watching it, it’s hard to imagine our seas without a plethora of weird and wonderful creatures at every depth. Let’s hope that enough can be done to ensure that in the future, we still see this menagerie of life in our oceans, not just on film.

For those lucky enough to currently be watching in the UK, Blue Planet II continues at 8pm on Sunday on BBC One, while those in the US will be able to catch it on BBC America at a later date.