James Cameron is currently writing an 'Avatar' ''bible'' on which he will base the script for the sequel to the sci-fi adventure movie.
James Cameron is writing a "bible" about the world of 'Avatar' before he pens the sequel.
He said: "At the moment, he's still writing what he calls 'The Bible' and detailing the world. Once he's detailed the world - more so than it's already detailed in his big brain, anyway - then, he said he can write the script, and we can go explore the world.
"Things like going underwater, going into the floating mountains."
The 34-year-old star adds Canadian-born James has had some "really cool" ideas about what the sequel would entail.
He said: "We've been discussing that with Jim. He has had some ideas he told us, while we were filming, which were really cool and out there."
Discussing his on-screen relationship with Netiri, played by 'Star Trek' actress Zoe Saldana, Sam added he was excited to find out what has happened to his character Jake, who is now living in a genetically-engineered alien body.
He told Moviefone: "I always joked and said that they were married and Jake Sully got lazy and Netiri kicked his butt. But there is something to the notion of being in a genetically-engineered body now, which he is. Is there a 'use-by' date on it? I don't know.
"What's the new dilemma? Is it just humans coming back, or is something even bigger than can threaten them, can threaten the world? We can look at our world again and see that we know we're hurting the environment, and we know we can do things about it. But what else are we doing that's wrong so it can reflect on our own life?"
'Avatar' - which grossed $2.7 billion worldwide - is set to have two follow-up movies, the first of which is due in December 2014.