Titanic director James Cameron successfully returned to the ocean surface after he plunged to the deepest part of the Pacific Ocean's Mariana Trench, southwest of Guam, on his solo expedition.

The filmmaker arrived at the site known as Challenger Deep shortly before 8 am local time on Monday, reaching a depth of 35,756 feet, or roughly seven miles beneath the ocean's surface, said the National Geographic Society, which is overseeing the expedition, reported Reuters.

Cameron tweeted: "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 director who made the dive aboard his 12-tonne lime-green sub called Deepsea Challenger became the first human to reach the 6.8-mile-deep (11-kilometre-deep) undersea valley alone. His return was a faster-than-expected 70-minute ascent, according to National Geographic.

With this successful expedition, James Cameron also became the third person to touch the deepest point after Jacques Piccard, a Swiss engineer, and Don Walsh from the US navy who made the first historic dive in a bathyscaphe called the Trieste in 1960.

Both Piccard and Walsh were able to spend only about 20 minutes there and could not see much after their sub kicked up sand from the sea floor, reported the Guardian.

Cameron, who reached the bottom in two hours and 36 minutes, spent hours collecting some scientific data and other specimen.

According to BBC, the Deepsea Challenger was made in Australia. Cameron, who financed the expedition, was spending the last few years working in secret with his team of engineers to design and build the craft, which weighed 11 tonnes and is more than 7m (23ft) long.

Cameron is expected to announce his initial findings and after analysis, the findings will be published in the National Geographic magazine.

Click here to check the video of Cameron's dive to the earth's deepest point.

National Geographic has released footage of James Cameron’s trek 6.8 miles into the deepest section on the face of the Earth.Reuters/National Geographic
Oscar-winning director James Cameron has resurfaced on Monday after embarking on a deep sea dive to one of the deepest known sections of the Earth, the Challenger Deep in the Mariana Trench.Reuters/ National Geographic
Crews prepare the Deepsea Challenger for its first test in the ocean at Jervis Bay, south of Sydney in this handout photo released to ReutersReuters/National Geographic