Avatar crew created a new style of swimming for The Way of Water and used James Bond-style jetpacks to make the Na'vi's underwater movements as 'accurate' as possible

James Cameron and his Avatar team always go above and beyond when it comes to creating Pandora and the life found on the alien planet – but this is something else.

As revealed in the new Disney Plus documentary Fire and Water: Making the Avatar Films, the crew and swimming experts helped create a new style of swimming to better replicate the Na'vi's body proportions and unique flat-headed tails.

With the need for the Na'vi's underwater swimming to require a very un-human-like lack of movement, director James Cameron enlisted the help of world champion freediver and 'stroke consultant' William Trubridge (presumably, the first of his kind on any movie, ever) to create something wholly original on screen.

"We came up with a free-diving stroke called a keyhole," Cameron recalled.

Describing the movement, Trubridge added, "You're using your hands and feet kind of like paddles and sweeping them in big movements through the water."

While the sweeping, fin-like movement is – more or less – what ended up in the final cut, the new style of swimming had one major aquatic roadblock: the actors couldn't gain the necessary speed to kick off without moving their hips and legs in the usual fashion.

Any other director, perhaps, would have likely shrugged their shoulders and glossed over the Na'vi's movements on-screen as a quirk of performance capture. Not James Cameron. Instead, he decided to unleash his inner Q with some James Bond-style gadgetry. MI5, eat your heart out.

"They're not gonna go anywhere during that glide phase, because they're not going to generate enough thrust," Cameron said. "So, then we thought: propulsion. We found these little jetpacks and gave [the actors] a little switch so they could do the stroke and then they could hit that switch on the little jet-propulsion unit. They got very, very good at it."

Fire and Water: Making the Avatar Films is now streaming on Disney Plus. A third Avatar movie, titled Fire and Ash, hits cinemas on December 19.

For more, check out our guide to upcoming movies.