INCREDIBLE LOCATIONS, FANTASTICAL SCENES

Production teams went to every continent and worked across every ocean to make the new series, which features scenes from icy polar waters to shimmering coral reefs and storm-battered coastlines.

They also went deep. Very deep. Producer Orla Doherty says she spent more than 500 hours in submersibles going to a depth of 1 000m below the surface – the deepest the technology could take them.

Only three humans have gone deeper. In the ’60s Don Walsh and Jacques Piccard became the first explorers to dive 11km into the Mariana Trench, and in 2013 James Cameron made a record-breaking solo dive into the trench.

“You can’t go to the toilet the whole time you’re down there, so you have to hold it for 10 hours,” Doherty told The Guardian.

But, boy, was it worth it! “It’s like all the sci-fi films you’ve ever watched rolled into one,” she said.

“We saw Humboldt squid on the attack, which no one has filmed before. These are two-metre monsters – fierce, voracious predators – and we were surrounded by a squadron of a thousand of them.

“We even saw their far darker side, when they turn on each other and become cannibals if there isn’t enough food.”