The Alien actor, who starred in the original 2009 sci-fi film as biologist Grace Augustine, will reprise her role in the sequels, the second of which recently finished filming in New Zealand.
But with much of the action in the new films taking place underwater, Weaver admitted that filming had been a demanding process for which she was required her to train with military divers to hold her breath for more than six minutes.
“I had some concerns,” the 71-year-old told The New York Times. “But that’s what the training was for. And I really wanted to do it.”
She continued: “I didn’t want anyone to think, ‘Oh, she’s old, she can’t do this.’”
While filming underwater, Weaver had weights attached to her waist, with a team of professional divers on hand to take her back to the surface at regular intervals.
However, she said that she thoroughly enjoyed the process and being tested on set.
“My hope is that what I receive from the universe is even more outrageous than anything I can think of,” she said.
“I don’t really say to myself, ‘Well, you can’t do this.’ Or, ‘You can’t do that.’ Let me at it! And we’ll see.”
The three other sequels have also been pushed back by a year, meaning the five-film Avatar franchise will finally be completed by Christmas 2028.