David Attenborough may have only just blessed us with blockbuster series Planet Earth II, but now he is gearing up to show viewers the mysteries of of Earth's oceans - with the announcement of Blue Planet II. 

The 90-year-old veteran broadcaster and naturalist will be presenting the seven-part series airing on BBC1 later this year. 

It has been 16 years since The Blue Planet revolutionised the public's understanding of life beneath the waves. The BBC is hoping its sequel will echo the success of Planet Earth II, which averaged over 10 million viewers per episode. 

The Blue Planet used pioneering filming techniques, but the broadcaster has promised that Blue Planet II, filmed by its Natural History Unit over four gruelling years, will feature even more ambitious filming and a "fresh cast of extraordinary aquatic animals" from every ocean in the world. 

In a statement, David Attenborough commented: “I am truly thrilled to be joining this new exploration of the underwater worlds which cover most of our planet, yet are still its least known."

As for the cast of "extraordinary aquatic animals", that's no overstatement.

Viewers will meet hairy-chested Hoff crabs, snub fin dolphins that spit water through the air, and and a tool-using tusk fish never before captured on film. Then there's footage from a dive with a sperm whale mother and calf who head deep into the abyss to hunt.

Executive producer James Honeyborne said: "The oceans are the most exciting place to be right now, because new scientific discoveries have given us a new perspective of life beneath the waves.

"Blue Planet II is taking its cue from these breakthroughs, unveiling unbelievable new places, extraordinary new behaviours and remarkable new creatures. Showing a contemporary portrait of marine life, it will provide a timely reminder that this is a critical moment for the health of the world’s oceans.”

Camera teams will take viewers from icy polar seas to colourful coral atolls to the black depths of the deep ocean, showing off the Gulf of Mexico's methane volcanoes and the "Boiling Sea" in the Pacific Ocean.

Massively improved technology since 2001 will also help Attenborough tell his tale. The team use two manned submersibles to explore the Antarctic depths at 1000m for the first time, while "suction cams" enable viewers to "travel" on the back of whale sharks and orcas. 

Planet Earth II will air later in 2017