In the film, Pandora is depicted as being located in the Alpha Centauri A system approximately 4.37 light-years (276,000 AU) away from Earth. It is one of the many natural satellites orbiting the gas giant Polyphemus, named for the Polyphemus of Greek mythology. Pandora's atmosphere is a mix of nitrogen, oxygen, carbon dioxide, xenon, ammonia, methane, and hydrogen sulfide. Humans cannot breathe this, so they wear Exo-Packs when outside their buildings or vehicles.
Pandora has lush, tropical rainforests that cover much of its continents. Pandora also possesses a lesser gravitational force than Earth does. The geology of Pandora is strongly affected by the presence of unobtanium, a mineral whose superconductive properties allow it to float in magnetic fields. This property makes it highly valued by humans, who mine it for transport back to Earth. Pandora's levitating Hallelujah Mountains contain significant quantities of unobtanium, which allows them to ride the strong magnetic fields in their region.
Conceived for the film was the Na'vi language, a constructed language often spoken by the actors when they played Na'vi characters. The Na'vi language was created by communications professor emeritus and linguistics consultant Paul Frommer of University of Southern California. He designed the language so it could be spoken by human actors, combining syntactic and grammatical rules from other existing languages. Frommer created over a thousand words for the Na'vi language and coached the actors who played Na'vi characters on speaking it for the film. When communicating to humans in the film, Na'vi characters – especially Neytiri – speak in accented and broken English.
Leri Greer, a designer at Weta Workshop, explained the unusual day/night cycle experienced by the Na'vi, who inhabit a moon orbiting a planet, that in turn orbits around a star.
According to Cameron, the appearance of the Na'vi character Neytiri had some specific inspirations and requirements: she was inspired by Raquel Welch's character in Fantastic Voyage and by Vampirella, noting in the latter's case, "the fact didn’t exist didn’t bother me because we have these quintessential female images in our mind, and in the case of the male mind, they’re grossly distorted. When you see something that reflects your id, it works for you.... Right from the beginning I said, 'She’s got to have tits,' even though that makes no sense because her race, the Na’vi, aren’t placental mammals. I designed her costumes based on a taparrabo, a loincloth worn by Mayan Indians."