We all feel a deep connection to Earth’s oceans. They are by turns tempestuous and serene, exquisitely beautiful and bleakly forbidding. They are the lifeblood of the planet: driving our weather, regulating our climate and ultimately supporting all life on Earth. They cover 70% of Earth’s surface, and yet they remain the least explored places on the planet.

Twenty years ago, 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.

In recent years, our knowledge of what goes on beneath the waves has been transformed. Blue Planet II uses breakthroughs in science and cutting-edge technology to explore new worlds.

Over the course of more than four years in production, the Blue Planet II team mounted over 125 expeditions, visited 39 countries, and filmed off every continent and across every ocean. Crews spent over 6,000 hours diving underwater, filming everywhere from our familiar shores to the deepest seas.

On remote island shores, they found leaping blennies – fish that live almost exclusively on land – and giant trevally that snatch seabirds out of the air. In vibrant coral wonderlands, they filmed the ingenious coral trout – which enlists the help of an octopus to flush little fish out of the reef – and the tusk fish, which uses a tool to crack open clams.

In cooler seas they explored mysterious underwater forests, and in sea grass, they encountered an army of giant spider crabs and watched 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, they found Portuguese man of war sailing the ocean’s trade winds in search of food, and super-pods of false killer whales that form an unlikely partnership with families of bottlenose dolphins.

The final frontier of our blue planet is the deep ocean. Here, after 1,000 hours in submersibles, Blue Planet II turns the spotlight on creatures so alien they could be from another planet.

Our great oceans hold countless previously-untold stories. But they are also essential to all life on Earth. They moderate our climate, create our weather, and generate about half our planet’s oxygen. Blue Planet II’s exploration of Earth’s oceans, reveals an uncomfortable fact: the health of our ocean is under threat. The oceans are changing at a rate faster and in more ways than in the whole of human history. 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 unexpected new landscapes. Methane volcanoes erupt a kilometre below the surface of the Gulf of Mexico. In the Pacific, the team witness the so-called ‘boiling sea’ phenomenon. Manned submersibles explore the Antarctic deep at 1000 metres 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. New filming technologies include: Ultra High Definition tow-cams that allow predatory fish and dolphins to be filmed head-on; suction-cams which enable the viewer to travel on the back of large creatures such as whale sharks and orcas; and Ultra High Definition probe cameras that immerse the viewer into the world of miniature marine life.

New Relevance: Blue Planet II introduces compelling and contemporary stories concerning issues such as the way that plastics contaminate our oceans, widespread coral bleaching and the profound impact of our warming seas.