James Cameron is up against bids by three other ocean submersibles, including ones backed by Google’s Eric Schmidt and Virgin tycoon Richard Branson, to reach an area called Challenger Deep in the Mariana Trench near Guam in the Western Pacific.

At 35,814ft down - close to seven miles - it could contain 29,029ft Mt Everest with room for twice the length of the world’s tallest building, Dubai’s 2,723ft Burj Khalifa.

Cameron, 57, who will pilot the dive himself, is almost ready, according to a rival.

“James Cameron has been working on it for many years and has a lot of good people around him. I think he will do it this summer,” the Sun quoted Bruce Jones, boss of the Triton 36000 bid in the US, as saying.

Canadian Cameron’s craft is so small that he will need to sit in a foetal position for the two-hour descent.

The race marks over 50 years since the feat was achieved for the only time, by US Navy Lieutenant Don Walsh, now 80, and Swiss engineer Jacques Piccard.

Their submersible took five hours in 1960 and kicked up so much sediment they could not take a photo. The 60s space race meant their brave achievement went largely overlooked.

Cameron’s rivals include DeepSearch, a 25 million pound three-seater sub backed by Google boss Schmidt and oceanographer Sylvia Earle.

Branson’s Virgin Oceanic is an 18ft-long submersible which cost 6 million pounds. Its stubby wings will allow it to “fly” underwater. Branson also plans to set a record by going to the bottom of the five oceans for a BBC film.

Trition 36000 is a 9 million pound three-seater made of specially-adapted glass.

Jones predicts it will be ready in two years, but he doesn’t have much faith in Branson’s machine.

“My feeling is the Virgin effort is not viable… It was not initially designed for this mission,” he said.