Attendees at the CinemaCon movie theater industry summit were invited to don 3D glasses and return to Pandora, with first footage of "Avatar: The Way of Water" showing Na'vi characters swimming beneath the planet's oceans and soaring through its skies.

The movie, which will be released in December, is the first of four planned sequels to the $2.8 billion-grossing original from 2009.

"I can assure you it's been well worth the wait," said Disney distribution chief Tony Chambers, confirming the film's name.

Cameron addressed CinemaCon via video from New Zealand, where finishing touches are being put in place on the film.

He promised giant technological leaps forward from the original, whose main characters Jake Sully (Sam Worthington) and Neytiri (Zoe Saldana) now have a family.

"We set out once again to push the limits of what cinema can do," said Cameron.