Hollywood icon James Cameron has made it to what is believed to be earth's deepest point, and has returned to the Pacific Ocean's surface safely.
The director of "Titanic", "Avatar" and other films used a specially designed submarine to dive nearly 11 kilometres, completing his journey a little before 8am on Monday local time, according to Stephanie Montgomery of the National Geographic Society.
He plans to spend about six hours exploring and filming the Mariana Trench, about 320km southwest of the Pacific island of Guam.
"All systems OK," were Cameron's first words upon reaching the bottom, according to a statement.
His arrival at a depth of 10,898 metres came early on Sunday evening on the United States' East Coast, after a descent that took more than two hours.
The scale of the trench is hard to grasp - it is 120 times larger than the Grand Canyon and more than a 1.6km deeper than Mount Everest is tall.
Cameron made the dive aboard his 12-tonne lime-green submarine called the "Deepsea Challenger".
He planned to collect samples for biologists and geologists to study.
"It's really the first time that human eyes have had an opportunity to gaze upon what is a very alien landscape," said Terry Garcia, the National Geographic Society's executive VP for mission programmes, via phone from Pitlochry, Scotland.
The first and only time anyone dove to these depths was in 1960. Swiss engineer Jacques Piccard and US Navy Captain Don Walsh took nearly five hours to reach the bottom and stayed just 20 minutes.
They had little to report on what they saw, however, because their submarine kicked up so much sand from the ocean floor.
"He is going to be seeing something that none of us have ever seen before. He is going to be opening new worlds to scientists," Garcia said.
One of the risks of a dive so deep is extreme water pressure. At 10.9km below the surface, the pressure is the equivalent of three SUVs sitting on your toe.
Cameron told The Associated Press in an interview after a 8.2 kilometre-deep practice run near Papua New Guinea earlier this month that the pressure "is in the back of your mind."
The submarine would implode in an instant if it leaked, he said.
But while he was a little apprehensive beforehand, he was not scared or nervous while underwater in the practice runs.
"When you are actually on the dive you have to trust the engineering was done right," he said.
The film director has been an oceanography enthusiast since childhood and has made 72 deep-sea submersible dives.
Thirty-three of those dives have been to the wreckage of the Titanic, the subject of his 1997 hit film, which will be released in a 3-D version next month.