"They’re supposed to still be in high school and they look like they’re 27," the filmmaker says of the Hawkins teens.

Visual effects can only go so far in Hollywood.

James Cameron says he filmed Avatar sequel The Way of Water at the same time as the forthcoming third and fourth films to avoid what he called "the Stranger Things effect," coining a new phrase to describe the inevitable growth spurt of child actors on multiyear projects.

Trinity Jo-Li Bliss was about 7 when she was cast as Tuk in the sequel and is now 13, while 18-year-old Jack Champion, who plays Spider, was 12 and "growing like a weed," Cameron recalls to EW in a recent feature story. For that reason, the second and third films, as well as the first act of the fourth, had to be done in one production.

Avatar The Way of Water
Trinity Bliss' Tuk explores the waters around the Metkayina clan's home in 'Avatar: The Way of Water.'
| Credit: 20th Century Studios

"Otherwise, you get — and I love Stranger Things — but you get the Stranger Things effect where they're supposed to still be in high school [but] they look like they're 27," Cameron says. "You know, I love the show. It's okay, we'll suspend disbelief. We like the characters, but, you know."

Sam Worthington and Zoe Saldaña reprise their roles as Jake Sully and Neytiri in the Avatar sequel, and are now parents of four who must fight to protect their home when a familiar threat returns. While filming three films at once sounds daunting, Saldaña says it was a worthy undertaking.

"We did read-throughs, we discussed extensively where we were, we defined those beats that distinguished 2 from 3," she says. "So from where I was standing, I never felt that it was uncomfortable or anything, but that just has to do with the amount of time that we took in preparation for this."

"Jim makes you a part of the whole process and hears you," Saldaña adds. "Every need that you have, he takes great attention to that detail and tries to the best of his ability to accommodate and incorporate your input."

Avatar The Way of Water
Jack Champion as Spider in 'Avatar: The Way of Water'
| Credit: 20th Century Studios

As for what the forthcoming sequels will entail, franchise producer Jon Landau confirms each movie will introduce audiences to new biomes.

"Each movie is going to introduce audiences to new clans, new cultures on Pandora," he tells EW. "Once we introduce a character, they stay a part of the ongoing evolution. We just add to it. So you can expect to see the Metkayina that you meet in this movie in subsequent movies. There are other clans that we'll introduce in movie 3 that you'll see in movie 4 and so on and so forth."

The third installment of the Avatar franchise is scheduled for a Dec. 20, 2024 release date.

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