Blue Planet ll begins at 8pm on BBC1, with David Attenborough narrating an episode full of inky black oceans and extraordinary creatures.

(The programme airs in the UK on Sunday nights on BBC1 at 8pm GMT)

An introduction by James Honeyborne, Executive Producer

The ocean is by turn tempestuous and serene, exquisitely beautiful and bleakly forbidding. It covers 70% of Earth’s surface, and yet remains the least known part of our planet. At first glance, it may seem as alien a world to us, as we are to it, but with the latest diving and submarine technologies, it’s possible to explore the oceans today like never before. We can stay submerged deeper, for longer, and in doing so, we discover that we have more in common with, and are more connected to the ocean than we ever imagined.

Our seas are home to some of the most spectacular events and compelling animal characters in nature. Sea creatures that reveal their surprising intelligence, leading complex lives which, in some cases, even begin to mirror our own. If we didn't already feel that deep connection to the ocean and its inhabitants, then perhaps now we will.

It all started some twenty years ago, when a team of wildlife film makers from the BBC’s Natural History Unit set out to make a series on the world’s oceans, the breadth and scale of which had never been seen before. Broadcast in 2001, the multi-award winning The Blue Planet, narrated by Sir David Attenborough, cemented the Unit’s peerless reputation for underwater filming.

Now, a generation on, the NHU has returned to these underwater worlds for Blue Planet II. And in recent years, our knowledge of what goes on beneath the waves has been transformed. Blue Planet II uses breakthroughs in marine science and cutting-edge technology to explore new worlds and reveal the very latest discoveries.

Over the course of more than four years in production, our teams mounted 125 expeditions, visited 39 countries, and filmed on every continent and across every ocean. Our crews spent over 6,000 hours diving underwater, filming everywhere from our familiar shores to the deepest seas. Such endeavor, passion and commitment has resulted in a series that brings us closer than ever before to the captivating lives of some of the most extraordinary sea creatures, transporting us into their magical worlds.

On remote island shores, we found leaping blennies - fish that live almost exclusively on land - and giant trevally that snatch seabirds out of mid-air. In vibrant coral wonderlands, we filmed the ingenious coral grouper - a fish that enlists the help of an octopus to hunt little fish hiding amongst coral branches - and, perhaps most charming of all, the ingenious and industrious tusk fish, who uses an anvil to crack open his clams.

In cooler seas we explored mysterious underwater forests. Amongst meadows of seagrass, we encountered an enormous army of giant spider crabs on the march. And we witnessed vast plankton blooms that spark a feeding extravaganza for thousands of dolphins, sea lions and whales.

Journeying into the giant void of the open ocean, we found Portuguese man-o-war sailing the ocean’s trade winds in search of food and happened upon super-pods of false killer whales that team up with families of bottlenose dolphins to hunt.

The ocean’s final frontier is the deep - Earth's ‘inner space’. Here, after 1,000 hours in submersibles, Blue Planet II turns the spotlight on creatures so alien they could have come from outer space. It’s said we know less about the depths of our own planet than we do the surface of Mars.

Our great ocean holds countless previously-untold stories. But the seas are also essential to all life on Earth. Not only do they moderate our climate and create our weather, they also generate about half our planet’s oxygen. But while filming Blue Planet II we have also witnessed great changes: the health of our ocean is under threat. Never has there been a more crucial time to explore our remotest seas, and to examine what the future might hold for our blue planet.

New Landscapes

Blue Planet II will bring viewers face to face with unexpected new landscapes. Methane volcanoes suddenly erupt 650 metres below the surface of the Gulf of Mexico. In the Pacific, our team witness the phenomenon of the so-called ‘Boiling Sea’. Manned submersibles explore metres deep off Antarctica for the very first time.

New Technology

Revolutionary technology allows us to enter new worlds, and film new behaviours in ways that were impossible just a generation ago: tow-cams to film predatory fish and dolphins head-on, as they charge through the ocean at top speed; suction-cams which enable the viewer to ride on the back of large creatures such as whale sharks and orcas; and Ultra High Definition probe cameras that allow us/them to get eye-to-eye with the smallest of creatures.

New Relevance

Blue Planet II introduces compelling and contemporary stories concerning issues from the parts of our ocean awash with plastics to the devastating coral bleaching events of recent years and the profound impacts of our warming seas. We will reveal how the health of our ocean matters to us all.

Blue Planet ll on BBC1 at 8pm