To boldly go under: Director James Cameron embarks on his record-breaking descent SEVEN miles to the bottom of Pacific's Mariana trench

ORIGINAL: Daily Mail

By Rob Waugh

UPDATED: 16:00 GMT, 22 March 2012

• Aims to be first human to visit bottom since January 1960
• Solo submersible so cramped he can't move his arms
• First of several competing missions to deepest point on Earth
• Mariana Trench is deeper than Everest is high
• The descent takes about 90 minutes
• Cameron will film the journey for a feature-length documentary

Avatar director James Cameron's attempt to be the first human being in 50 years to visit the deepest point on Earth - the bottom of the Mariana Trench, seven miles down in the Pacific - is under way.

The director aims to become the first of at least four teams racing to the ocean floor, an icy, alien environment with pressures 1,000 times higher than the surface.

Many liken the journey to man's steps into space. 'The deep trenches are the last unexplored frontier on our planet," says Cameron.

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James Cameron emerging from the hatch of Deepsea Challenger - the tiny submarine the director will use to travel to the bottom of the Pacific's Mariana trench

James Cameron's team prepare Deepsea Challenger for its first test in the ocean at Jervis Bay, south of Sydney, Australia. In the coming weeks the submersible will travel to the bottom of the Mariana Trench

James Cameron (far right) and Don Walsh (far left), who was aboard the only other successful manned descent to the Mariana Trench in 1960 

Jacques Piccard and Don Walsh emerge from the bathyscaphe Trieste following their successful manned descent to the bottom of the Mariana Trench in January 1960. In the coming weeks, 52 years later, explorer and filmmaker James Cameron aims to repeat the feat

Deepsea Challenger, the submersible designed by explorer and filmmaker James Cameron and his engineering team to travel to the bottom of the Mariana Trench, is lowered into the water for testing

The only people who have ever reached the bottom of the Mariana Trench were Jacques Piccard and Don Walsh, who used the huge, blimp-shaped submersible Trieste in January 1960.

The director recently completed a test dive of five miles in Papua New Guinea, using his solo submersible Deep Sea Challenger.

Cameron had to build his own vehicle for the attempt - a craft capable of withstanding 1,000 atmospheres of pressure.

Cameron is inside a pilot sphere - the shape most able to resist pressure - so cramped he will not be able to extend his arms.

He will be the sole occupant in a complex, 24-foot-long craft made primarily of highly specialised glass foam.

The descent will take around 90 minutes and he will spend around six hours at the bottom, filming the attempt for a 3D documentary.

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Pictured: Stunning photos of the Titanic shown on the base of the ocean nearly 100 years from that fateful night (2012 marks the centennial of  that event)

Protection: Cameron will command the sub from a spherical cockpit - the best shape for withstanding pressure

Rolex sent a watch down with the Trieste in 1960 and produced another timepiece for Cameron's odyssey.

It's a complete one-off and not for sale - and is capable of withstanding the extreme pressures of the Mariana Trench - and more - right down to 12,000m.

Cameron looks set to beat rival teams to the bottom - Sir Richard Branson's Deep Flight Challenger, and DOER Marine, backed by Google's Eric Schmidt.

A Florida company, Triton submarines, are working on a submarine that will take people to the bottom for $250,000 a ticket.

A unique Rolex watch will also be journeying to the bottom with Cameron. Time for deep exploration: A one-off Rolex capable ofwithstanding pressure down to 12,000mis attached to the side of the sub

'I've always dreamed of diving to the deepest place in the oceans,' says Cameron. 'For me it went from a boyhood fantasy to a real quest, like climbing Everest.'

'There is currently no commercial submersible on Earth capable of diving to the ‘full ocean depth’ of 36,000 feet. The only way to make my dream a reality was to build a new vehicle unlike any in current existence,' says Cameron.

In-water testing of the submersible that explorer and filmmaker James Cameron will pilot to the bottom of the Mariana Trench

Swinging above the docks in Guam's Apra Harbor is the Trieste, the submersible that took Don Walsh and Jacques Piccard on the first and only successful manned dive to the bottom of the Mariana Trench

Deep-water testing of tthe submersible that explorer and filmmaker James Cameron will pilot to the bottom of the Mariana Trench

Deepsea Challenger undergoes deep-water testing in preparation for Cameron's dive

The measurement - using echosound - of Challenger Deep, the deepest point of the Marianas trench may be the most accurate yet

The Mariana trench: The last visitors to the bottom went there in January 1960

A 'hydrographic' ship from the U.S. Navy recently mapped the Marianas trench from north to south using a 'multibeam echosounder', a standard device for mapping the ocean floor.

The ship, associated with CCOM, the Centre for Coastal and Ocean Mapping at the University of New Hampshire, mapped the whole of the Marianas Trench to a 100m resolution - including an accurate 'map' of the deepest place on earth, Challenger Deep

Cameron is an avid explorer with 72 submersible dives to his credit—51 of which were in Russian Mir submersibles to depths of up to 16,000 feet, including 33 to Titanic.

Sub Sphere: What Protects Human Deep Divers?