The long due sequel to the record-breaking "Avatar" movie is one step closer to its debut. "Avatar 2" and three more installments officially started production on Monday, Sept. 25, all of which have a collective budget of over one billion dollars.

Deadline reports that the principal photography kicked off at Manhattan Beach still with James Cameron at the helm. It's unclear how much each movie really cost. However, the original "Avatar" notably had an estimated budget of almost $240 million, so $1 billion would see these four sequels average $250 million apiece.

Cameron plans to shoot all sequels back-to-back, which means he will be working for the franchise from now until 2025. "Avatar 2" is slated to open in theaters on Dec. 18, 2020, and the third movie on Dec.17, 2021. Then, there will be a three-year hiatus in releases, as "Avatar 4" will not premiere until Dec. 20, 2024, while the fifth installment will come out on Dec.19, 2025.

All four films are expected to be shot in 3D, a great factor which contributed to the original one's box office gross.

Several original cast members are already confirmed to return including Sam Worthington, Zoe Saldana, Joel David Moore, Stephen Lang, Matt Gerald and Sigourney Weaver. According to Coming Soon, Cliff Curtis of "Fear the Walking Dead" and Oona Chaplin of "Game of Thrones" will also appear in the films.

The humans are still expected to be the villains of the next installments, with the environmental themes of the first movie being explored once more.

There's no estimate yet as to how long the filming will take. However, since the last installment will not be hitting the big screen until nearly another decade, there might be regular breaks in production over the next few years. This way, the cast can work on other projects and the crew can have time to familiarize themselves with new technologies for the films.

Produced by Cameron himself and Jon Landau through their Lightstorm Entertainment, the sequels are written also by Cameron alongside Rick Jaffa, Josh Friedman, Shane Salerno, and Amanda Silver.