In 2006, Cameron stated that if Avatar was successful, he hoped to make two sequels to the film.[301] In 2010, he said the film's widespread success confirmed that he would.[302] He included certain scenes in the first film for future story follow-ups.[301][303] Cameron planned to shoot the sequels back-to-back and to begin work "once the novel is nailed down".[304] He stated that the sequels would widen the universe while exploring other moons of Polyphemus.[293] The first sequel would focus on the ocean of Pandora and also feature more of the rainforest.[305] He intended to capture footage for this sequel at the bottom of the Mariana Trench using a deepwater submersible.[306] In 2011, Cameron stated that he was just starting to design the ocean ecosystem of Pandora and the other worlds to be included in the story. The storyline, although continuing the environmental theme of the first film, would not be "strident" since the film will concentrate on entertainment.[307]
The sequels would continue to follow the characters of Jake and Neytiri.[308] Cameron implied that the humans would return as the antagonists of the story.[309] Worthington and Saldana signed on to reprise their roles in the sequels.[303] In 2010, Cameron confirmed that Sigourney Weaver[310] and Stephen Lang were also expected to return despite the demise of their characters.[311] The sequels were originally scheduled for release in December 2014 and 2015.[312] In 2011, Cameron stated his intention to film the sequels at a higher frame rate than the industry standard 24 frames per second, in order to add a heightened sense of reality.[313][314]
In 2012, Cameron first mentioned a possible third sequel.[315] That year, Cameron stated that the sequels were being written as "separate stories that have an overall arc inclusive of the first film", with the second having a clear conclusion instead of a cliffhanger to the next film. Cameron expected to release Avatar 2 in 2015.[316] In 2013, it was confirmed that there would be three sequels. Screenwriters were also announced: Josh Friedman for the first, Rick Jaffa and Amanda Silver for the second, and Shane Salerno for the third. Production was re-scheduled for 2014 with the films to be released in December 2016, 2017, and 2018.[317] Steven Gould was engaged to write four novels based on the films.[318] Later that year, Cameron announced that the sequels would be filmed in New Zealand, with performance capture to take place in 2014. An agreement with the New Zealand government required at least one world premiere to be held in Wellington and at least NZ$500 million (approximately US$410 million at December 2013 exchange rates) to be spent on production activity in New Zealand, including live-action filming and visual effects. The New Zealand government announced it would raise its baseline tax rebate for filmmaking from 15% to 20%, with 25% available to international productions in some cases and 40% for New Zealand productions (as defined by section 18 of the New Zealand Film Commission Act 1978).[319][320]
In April 2014, Cameron expected to finish the three scripts within six weeks, stating that all three sequels would be in production simultaneously and were still slated for December 2016 to 2018 releases.[321][322] He stated that although Friedman, Jaffa and Silver, and Salerno are each co-writing one sequel with him, they at first all worked together on all three scripts: "I didn't assign each writer which film they were going to work on until the last day. I knew if I assigned them their scripts ahead of time, they'd tune out every time we were talking about the other movie."[323][324] "We... worked out every beat of the story across all three films so it all connects as one, sort of, three-film saga."[325] Cameron also stated that Weaver would be featured in all three sequels and that her character Grace Augustine would be alive.[326] In March 2015, however, Weaver said that she will play a new character in the next film.[327]
By 2015, the scheduled release dates for the sequels were each delayed by another year, with the first sequel expected to be released in December 2017; Cameron called the writing process "a complex job".[328][329] In June 2015, James Horner, who was reported to be engaged to write music for the franchise, was killed in a plane crash.[330] In December, Cameron stated that he was "doing another pass through all three scripts ... Just refining. That’s in parallel with the design process. The design process is very mature at this point. We’ve been designing for about a year and a half. All the characters, settings and creatures are all pretty much [set]."[331] The following month, Fox announced a further release delay.[332]
As of February 2016, production of the sequels was scheduled to begin in April 2016 in New Zealand.[333] In April 2016, Cameron announced at CinemaCon that
there will be four Avatar sequels, all of which will be filmed simultaneously, with release dates in December 2018, 2020, 2022 and 2023, respectively.[334][335]