Cameron says he is planning an attempt to reach the world's deepest point, nearly seven miles below the ocean's surface. The dive will happen in a specially designed submersible in the next few weeks.
The venture is part of a joint scientific project between Cameron and the National Geographic Society, for whom the filmmaker was named an explorer-in-residence in 2011. Cameron hopes to capture images and data, and find out whether fish can live in the sea's deepest reaches.
Cameron will be the first person to descend to the bottom of the Mariana Trench, known as the "Challenger Deep," since a two-man U.S. Navy expedition did it in 1960.
Those explorers spent just 20 minutes on the ocean floor, according to the National Geographic Society. Cameron will spend six hours at the bottom of the trench, collecting scientific samples.
"The deep trenches are the last unexplored frontier on our planet, with scientific riches enough to fill a hundred years of exploration," Cameron said in a statement.
This week, Cameron made a five-mile descent off the coast of Papua, New Guinea - a record for a solo dive.
The extreme pressure at such depths makes the expedition very risky.
"You'd be a fool not to think a lot about the dangers and hazards of this type of diving," said the director.
Cameron, who has been an oceanography enthusiast since childhood, has made 72 deep-sea submersible dives, including 33 to the Titanic.
The Associated Press contributed to this report.
