'Avatar," James Cameron's ecology-minded sci-fi epic, is turning out to be a renewable resource.

The DVD, which came out Thursday for Earth Day, should be a big seller, even though it includes no extras, trailers or bonus features (talk about conservation). A re-release of "Avatar" - already history's top-grossing film with a domestic total of $745 million, according to BoxOfficeMojo.com - is planned for August, with an additional six minutes of footage. Cameron also has said that yet another "Avatar" DVD, one with all the bells and whistles buyers have come to expect, may appear in November.

But the big news - though it will likely surprise no one - is that Cameron is planning a sequel and considering a trilogy.

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In an interview posted earlier this week on Hero Complex, the Los Angeles Times blog, Cameron said the sequel will return to Pandora, the fictional planet populated by the blue-skinned, computer-animated Na'vi tribe, but the story will focus on the ocean rather than the rain forest. (Cameron is known as an avid diver.) He promised that the underwater environment would be "equally rich and diverse and crazy and imaginative."

Cameron also said that the next "Avatar," unlike the original, will not take 10 years to hit the screen. The goal is to cut the time (and the budget) in half, though he also admits: "We won't accomplish that, but if we can reduce by 25 percent in both categories, we'll have really accomplished something."