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One of the great love stories of all time is now available on Blu-ray for the first time.

A 3D Blu-ray version of "Titanic" hit stores this week. It contains over two and a half hours of never-before-seen footage.

"Titanic" director James Cameron is fond of a new documentary in the collection called "The Final Word," which explores what happened to the ship once it sank. He told ABC News Radio's David Blaustein, "If you're really into kind of how the ship sank, I get the experts together and we sort of work it out and I think we come to some pretty good conclusions."

Cameron said his love for deep sea exploration was fostered by his research for the film, including his expeditions to the Titanic wreck. That helps explain why the sequels to another one of his blockbusters, "Avatar," will explore the ocean world on the moon Pandora.

What else can we expect from the "Avatar" sequels? Cameron revealed, "It's really going to be the completion of a major story arc that has to do with Jake and Neytiri and their children, and it's an epic multi-generational story."

Cameron said "Avatar 2? will be released on Christmas 2015 and "Avatar 3? on Christmas 2016. Cameron doesn't have a release date in mind just yet for a possible fourth "Avatar" flick, but he said the film could be a prequel.