''Titanic'' director James Cameron returned to the surface yesterday after a solo submarine dive to the deepest point in the world's oceans that was hailed as the ultimate test of "man and his machine." Cameron plunged about seven miles (11 kilometres) to the bottom of the Mariana Trench in the western Pacific, where temperatures are barely above freezing and the pressure is a crushing thousand times that at sea level. Speaking after the mission, the filmmaker-explorer described a barren "completely alien world" on the ocean floor, not unlike the surface of the moon. It was a "very lunar, very desolate place. Very isolated," Cameron said. "I felt like I, in the space of one day, had gone to another planet and come back," he said, describing the ocean floor as a "completely featureless, alien world." The acclaimed film director described the experience of hurtling down the "yawning chasm" of ...