Mariana Trench for several years and was finally able to complete that goal.
No news yet on what he saw down there...
At noon, local time (10 p.m. ET), James Cameron's "vertical torpedo" sub broke the surface of the western Pacific, carrying the National Geographic explorer and filmmaker back from the Mariana Trench's Challenger Deep—Earth's deepest, and perhaps most alien, realm.
The first human to reach the 6.8-mile-deep (11-kilometer-deep) undersea valley solo, Cameron arrived at the bottom with the tech to collect scientific data, specimens, and visions unthinkable in 1960, when the only other manned Challenger Deep dive took place, according to members of the National Geographic expedition.
After a faster-than-expected, roughly 70-minute ascent, Cameron's sub, bobbing in the open ocean, was spotted by helicopter and would soon be plucked from the Pacific by a research ship's crane. Earlier, the descent to Challenger Deep had taken 2 hours and 36 minutes.
Expedition member Kevin Hand called the timing of the DEEPSEA CHALLENGER sub's ascent "perfect."
Sources -> http://www.bbc.co.uk/news/science-environment-17503395