WASHINGTON -- A calm James Cameron has broken his own record with the world's deepest solo submarine dive, plunging 5.1 miles in the Pacific Ocean near Papua New Guinea, the filmmaker said Thursday.

But that's nothing. He said he plans later this month to descend to the deepest place on Earth.

Cameron is aiming to plunge to the bottom of Challenger Deep in the Mariana Trench of the Pacific Ocean, 200 miles southwest of Guam. It's 6.8 miles deep. Humans have been there only once before when a two-man U.S. Navy team went for just 20 minutes in 1960.

The "Avatar" and "Titanic" filmmaker said he wasn't frightened when he dove nearly that far in a practice run Wednesday that lasted 3.5 hours on the bottom.

"Certainly not nervous or scared during the dive," Cameron said. "You tend to be a little apprehensive ahead of the dive about what could go wrong. When you are actually on the dive you have to trust the engineering was done right."

Cameron is using a one-man, 12-ton lime green sub that he helped design called Deepsea Challenger. He is partnering with the National Geographic Society, where he is an explorer-in-residence.

"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 an earlier statement.

Cameron, who has been an oceanography enthusiast since childhood, has made 72 deep-sea submersible dives, including 33 to the Titanic, the subject of his 1997 blockbuster. A 3-D version of "Titanic" comes out April 4, timed to the 100th anniversary of the ship's sinking.