It probably won't surprise anyone, given the massive technical undertaking of the first movie, but the sequel to Avatar doesn't look as if it'll make its proposed 2014 release date. Producer Jon Landau spoke about the project, as well as the third movie in the series, in an interview with Empire where he said:
"Movies make release dates; release dates don't make movies.WETA are already working and we have our core team, (animation supervisor) Richie Baneham and (digital effects supervisor) Nolan Murtha, working with us. And we're working on underwater performance-capture.
"It's going to be like the Floating Mountains in the first movie. It's not going to be all underwater; it's going to be a place we go to, leave and come back to."
At least that explains why James Cameron has been spending so much time submerged under the sea of late!