James Cameron reveals first details of Kate Winslet's Avatar sequel character 

James Cameron reveals first details of Kate Winslet\'s

, in part, by reuniting with star Kate Winslet. The pair are currently filming

, the first of four planned continuations to Cameron’s record-setting 2009 blockbuster.

“She’s very excited about it. She blazed through for a couple of days of rehearsals and saw the world that we had created, and how we do the work, and she’s very excited,” Cameron told

The director previously revealed Winslet will star as Ronal in the film and explained to

that she’s “a character who’s part of the Sea People, the reef people.”

“The one thing she did do is demand that she do all her own water work,” Cameron said of Winslet. “I said, ‘All right, that’s fine, we’ll have to teach you how to free dive.’ The other actors are up to three- and four-minute breath holds. We’ve already been doing underwater capture. We did a scene last week with six teenagers, well, actually five teenagers and one 7-year-old underwater holding their breath for a couple minutes and acting, actually doing a dialogue scene under water because they speak kind of a sign language.”

Winslet’s casting was first announced in October. “Kate and I have been looking for something to do together for 20 years, since our collaboration on

, which was one of the most rewarding of my career. I can’t wait to see her bring the character of Ronal to life,” Cameron said previously.

film will focus on the offspring of Jake Sully and Neytiri (original stars Sam Worthington and Zoe Saldana, who will return for the sequels). “We never had this youthful element before, and that brings a different kind of energy to the film,”

producer Jon Landau told EW. “They represent the future generation of Pandora [the plant the film’s aliens, the Na’vi, call home] and play a very significant role — not just in this movie but throughout all the movies.”

is set to hit theaters in 2020, 11 years after the original. “It will be a natural extension of all the themes, and the characters, and the spiritual undercurrents,” Cameron told

of what fans should expect. “Basically, if you loved the first movie, you’re gonna love these movies, and if you hated it, you’re probably gonna hate these. If you loved it at the time, and you said later you hated it, you’re probably gonna love these.”