The Titanic director had to develop a special camera to withstand the 11km descent into the Pacific OceanFilm director James Cameron is planning to release a 3D film of his pioneering Marianas Trench dive in the Pacific Ocean, it was announced last night.Shortly after completing the 11km descent into Challenger Deep, the lowest known point on the Earth's surface, Cameron travelled to London to attend the premiere of the 3D version of his 1997 blockbuster Titanic . After the event, he told reporters that a 3D documentary of the dive, currently titled Deepsea Challenge, is being readied for a prospective cinema release later this year."We're shooting the whole expedition as a 3D film," Cameron said, explaining that the development of a new lightweight 3D camera, able to withstand the massive pressures at extreme depth, was crucial. "We spent a fair bit of the development budget of the sub figuring