Titanic director James Cameron has safely returned to the ocean surface after a solo submarine dive to the deepest part of the Pacific Ocean, expedition organizers said Monday, March 26.

"Jim Cameron has surfaced! Congrats to him on his historic solo dive to the ocean's deepest point," said a Twitter message from Deep Sea Challenge, which organized the dive.

Cameron is the first person to make a solo dive to the Pacific Ocean valley known as the Challenger Deep, southwest of Guam. And the last dive of any kind there was a relatively brief two-person team back in 1960.

After a faster-than-expected, roughly 70-minute ascent, Cameron's sub, bobbing in the open ocean, was spotted by helicopter and was expected to soon be plucked from the Pacific by a research ship's crane, organizers said.

Mission partner the National Geographic said Cameron had reached a depth of 35,756 feet (10,898 meters) at 7:52 am Monday (2152 GMT Sunday) in the Mariana Trench in his specially designed submersible.

Because of its extreme depth, the Mariana Trench is cloaked in perpetual darkness and the temperature is just a few degrees above freezing, according to members of the team.

The water pressure at the bottom of the trench is a crushing eight tons per square inch -- or about a thousand times the standard atmospheric pressure at sea level. Pressure increases with depth.

Cameron spent several hours on the Pacific Ocean sea floor, collecting samples for scientific research and taking still photographs and moving images.

His goal was to bring back data and specimens from the unexplored territory. He is expected to announce the results of the experiment later, AFP reported.