Director James Cameron returned safely to the surface on Monday after entering the history books as the first solo diver to reach the depths of the Mariana Trench. The filmmaker, whose 1997 blockbuster "Titanic" won 11 Oscars, has now embarked on 72 underwater journeys.
"I felt like I, in the space of one day, had gone to another planet and come back," Cameron said in a statement.
The nearly seven-mile voyage through near freezing temperatures, to what Cameron described as a "completely featureless, alien world" similar to that of the moon's surface, was captured on 3-D video and is expected to be aired on the National Geographic Channel.
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National Geographic said Cameron's trip in the submarine named the Deepsea Challenger took him 35,756 feet (10,898 meters) beneath the ocean's surface, traveling through miles of complete darkness.
"Falling through darkness—that's something that a robot can't describe," Cameron said. "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."
In the weeks leading up to the Mariana Trench dive, Cameron took part in a series of test dives, during which he set the world record for the deepest solo submarine run.
[Slideshow: More photos of the Deepsea Challenger]
Cameron's descent to the Challenger Deep valley of the Mariana Trench took two hours and 36 minutes. He had originally planned to spend about six hours at the bottom, collection soil samples and even wildlife that would be brought back to the surface for further study. However, problems with the submarine's hydraulic systems cut the exploration time down to just over two and a half hours.
It was the first journey to the bottom of the Mariana Trench in 50 years. Back in 1960, two explorers made the first-ever trip aboard U.S. Navy submersible Trieste but were unable to record visible images because of silt stirred up by their contact with the ocean floor.
After a 70-minute return trip to the surface, Cameron's "vertical torpedo" sub was spotted by helicopter and was lifted from the Pacific by a research ship's crane.
Expedition physician Joe MacInnis called Cameron's journey "the ultimate test of a man and his machine." The water pressure at the bottom of the Mariana Trench is eight tons per square inch, or about the 1,000 times the pressure at sea level.
Cameron's dive was closely watched by Microsoft co-founder Paul Allen, who was in attendance at the ocean's surface to watch Cameron's historic dive. Allen has been an avid supported of space exploration and owns the world's largest yacht, which comes equipped with its very own submarine.
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