A calm James Cameron has broken his own record with the world’s deepest solo submarine dive, plunging 8.2 kilometres in the Pacific Ocean near Papua New Guinea, the film-maker said.

The deep trenches are the last unexplored frontier on our planet, with scientific riches enough to fill a 100 years of exploration

Still, he is not satisfied. Later this month he says he plans to descend to the deepest place on earth.

Mr Cameron is aiming to plunge to the bottom of Challenger Deep in the Mariana Trench of the Pacific Ocean, 322 kilometres south west of Guam.

It is almost 11 kilometres deep deep. Humans have been there only once before when a two-man US Navy team went for just 20 minutes in 1960.

The Avatar and Titanic film-maker said he was not frightened when he dove nearly that far in a practice run that lasted 3.5 hours on the bottom.

“Certainly not nervous or scared during the dive,” Mr Cameron said in a ship-to-shore phone interview.

“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.” Later, he acknowledged that the bone-crushing pressure at eight kilometres and 11 kilometres deep “is in the back of your mind”.

Mr Cameron is using a one-man, 12-ton lime green submarine 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 100 years of exploration,” Mr Cameron said in an earlier statement.

Mr 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.