At Mariana Trench, James Cameron is king of the deep (photos)

Filmmaker James Cameron emerges from the Deepsea Challenger submersible.

Cameron piloted his specially designed solo submersible to a site known as "Challenger Deep," the deepest part of the Pacific Ocean's Mariana Trench -- about 6.8 miles down.

Cameron is the only individual ever to complete the dive in a solo vehicle, and the first person since 1960 to reach the very bottom of the world in a manned submersible.

The "Deepsea Challenge" expedition is being chronicled for a 3D feature film on the intensive technological and scientific efforts behind Cameron's dive.

Cameron and the Deepsea Challenge submersible are seen here being lowered into the Pacific Ocean at the start of his expedition on March 24.

At 7:52 a.m. local time on March 25, Cameron (@jimcameron) reached a depth of 35,755 feet and soon after issued what may be the world's deepest tweet: "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"

The Deepsea Challenge traveled at 3 to 4 knots on the way down, slowing as it neared the bottom.

Microsoft co-founder Paul Allen tweeted stats and updates from the surface, noting at one point that "James Cameron now the deepest solo diver in history, 3rd deepest ocean diver ever...25550 ft."

Cameron is met by ocean explorer and U.S. Navy Capt. Don Walsh, right, after completing his voyage.

Cameron in the hatch of the Deepsea submersible as he prepares for his dive.

Another shot of Cameron and ocean explorer Don Walsh (far right). Walsh was aboard the first manned vessel to reach the bottom of Challenger Deep 52 years ago, the Swiss designed bathyscaphe Trieste.