James Cameron

James Cameron has gone to the ends of the Earth and back.

On Monday morning, the Oscar-winning director dove to the deepest-known point on Earth, the Pacific Ocean's Mariana Trench southwest of Guam, becoming the first person to make the 6.8-mile dive alone.

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Cameron piloted a 12-ton submersible dubbed the Deepsea Challenger and arrived at the site, known as Challenge Deep, shortly before 8 a.m. local time, according to National Geographic, which oversaw the voyage. The 35,756-foot descent into the trench — which is 120 times larger than the Grand Canyon and a mile deeper than Mount Everest is tall — took two hours and 36 minutes. His first words after touching down were, "All systems OK."

"Just arrived at the ocean's deepest pt. Hitting bottom never felt so good. Can't wait to share what I'm seeing w/ you @DeepChallenge," Cameron also tweeted.

The Titanic and Avatar filmmaker spent about three hours on the bottom collecting research samples for marine biology, microbiology, astrobiology, marine geology and geophysics, and taking photographs and video footage. A joint venture between National Geographic, Cameron and Rolex, the expedition is designed to shed light on unknown locations of the Earth.

Following a faster-than-expected 70-minute ascent, Cameron, 57, reached the surface around noon.

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"This journey is the culmination of more than seven years of planning for me and the amazing Deepsea Challenge expedition team," Cameron said in a statement. "Most importantly, though, is the significance of pushing the boundaries of where humans can go, what they can see and how they can interpret it. Without the support of National Geographic and Rolex, and their unwavering belief that we could successfully make it to the deepest point in the ocean — and back — this would not have happened."

Only two other men have dove to Challenge Deep: Swiss oceanographer Jacques Piccard and U.S. Navy Lt. Don Walsh, who spent about 20 minutes there during their 1960 dive. Walsh is a consultant on the Deepsea Challenge expedition and was aboard the expedition ship Mermaid Sapphire during Cameron's trip.

Watch Cameron talk about his dive: