The Titanic film director was the first person to navigate the seven-mile-deep trench – the ocean’s deepest point, which is even 120 times larger than the Grand Canyon.

Encapsulated in a 12-tonne, lime green submarine, Deepsea Challenger, Cameron, 57, ventured Mariana Trench to shoot footage for a planned documentary.

His ship was equipped with 3D cameras and lighting provided by an eight-foot tower of LEDs.

“There is scientific value in getting stereo images because … you can determine the scale and distance of objects from stereo pairs that you can’t from 2D images,” Cameron told National Geographic News ahead of the dive. As he reached the bottom of the trench, which is about 200 miles south-west of the Pacific island of Guam, Cameron sent out a tweet reading: “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”.

The Mariana trench had not been explored since 1960, when Swiss engineer Jacques Piccard and US Navy Captain Don Walsh spent 20 minutes down there in 1960.

Expedition doctor Joe MacInnis said Cameron’s journey had been “the ultimate test of a man and his machine”, describing his friend as a real-life “avatar”. He said: “He’s down there on behalf of everybody else on this planet. There are seven billion people who can’t go, and he can. And he’s aware of that.”

Cameron is a long-time oceanography enthusiast.