"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 late Sunday.

"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.

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

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.

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

The research vessels Mermaid Sapphire and Barakuda waited for him on the surface during the dive.

"We're now a band of brothers and sisters that have been through this for a while," marine biologist Doug Bartlett told National Geographic from the ship before the dive.

Cameron's goal was to bring back data and specimens from the unexplored territory. He is expected to announce the results of the experiment later.

Upon touchdown, Cameron's first target was a phone booth-like unmanned "lander" dropped into the trench hours before his dive.

The submersible that Cameron designed, a "vertical torpedo" of sorts, had already successfully completed an unpiloted dive on Friday.

In 1960, a two-person crew aboard the US Navy submersible Trieste -- the only humans to have reached Challenger Deep -- spent just 20 minutes on the bottom, but their view was obscured by silt stirred up when they landed.

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, 57, has been running several miles a day, practicing yoga to increase his flexibility for the dive in the sub's cramped quarters and studying deep-ocean science, physician Joe MacInnis told National Geographic News.

MacInnis is a member of the DeepSea Challenge project, a partnership with the National Geographic Society and Rolex.

Cameron already has 72 dives under his belt, including 12 to film "Titanic."

The Mariana Trench is located in the western Pacific east of the Philippines and some 124 miles (200 kilometers) east of the Mariana Islands.

The crescent-shaped scar in the Earth's crust measures more than 1,500 miles (2,550 kilometers) long and 43 miles (69 kilometers) wide on average.