James Cameron Reached the Ocean's Lowest Point

To get to this point, Cameron and his crew have spent seven years reimagining what a submersible can be. The result is the 24-foot-tall (7-meter-tall) DEEPSEA CHALLENGER.

Engineered to sink upright and spinning, like a bullet fired straight into the Mariana Trench, the sub can descend about 500 feet (150 meters) a minute—"amazingly fast," in the words of Robert Stern, a marine geologist at the University of Texas at Dallas.

Pre-expedition estimates put the Challenger Deep descent at about 90 minutes.

By contrast, some current remotely operated vehicles, or ROVs, descend at about 40 meters (130 feet) a minute, added Stern, who isn't part of the expedition.

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.