Hollywood director James Cameron may be close to making a dive to the deepest place on Earth.
In a one-man submarine, he plans to dive 11km (seven miles) down beneath the waves to the bottom of the Mariana Trench, in the western Pacific.
There has only ever been one dive there, and that was half a century ago.
Mr Cameron and his team have set sail to reach the trench and are now waiting for a clear stretch of weather to begin the dive.
The BBC met up with the director in Guam, just before he set out for the high seas. This tiny tropical island is the nearest major landmass to the Mariana Trench – the focus of Mr Cameron’s ambition.
In the balmy heat, the team was making last-minute preparations for this journey to the deepest depth in the seas.
The Abyss and Titanic director has had a long-standing obsession with the oceans, but now he has created for himself the ultimate part.
In a prototype submarine, called the Deepsea Challenger, that fits just one person, he plans to make the first manned mission to the bottom of the trench for 50 years.
He says he came up with the idea while he was using submersibles to film a documentary on the wreck of the Bismarck, a German battleship that lies 4,800m (17,500ft) underwater.
“I started to think about what would it take to go deeper, what would it take to go to full ocean depth – that was kind of the holy grail from an engineering standpoint,” he told BBC News.
“So you start ‘noodling’ up designs, and thinking how it would be possible and what would it take. And then there is suddenly this moment that seems to transpire with no transition where you are suddenly doing it.”
He adds: “I seem to have that curse that once I imagine something being built, I have to build it.”
Mr Cameron and his team have spent the last few days in Guam, docked at the port, re-supplying the ship that has been their home for the last few months.
They arrived straight from Papua New Guinea, where the filmmaker performed a successful 8,200m test-dive. But the ultimate challenge will be to see whether their vessel can plumb the ocean’s deepest point.
They will need calm seas to launch and recover the sub – but while in the harbour, a strong wind has blown in, white caps topping the waves.
The team are doing everything they can to make the sub as safe as they possibly can – but the weather is out of their control.
The craft, which is housed on the ship’s deck in a large, air-conditioned hangar, is bright green, weighs 11 tonnes and is more than 7m (23ft) long.
Once in the ocean, it flips on its end, and descends vertically through the water column.
The compartment in which Mr Cameron will spend his nine-hour dive is tiny: a thick, metal sphere with an internal diameter of just 109cm (43in). He will be curled up inside, unable to stretch his arms or legs.
The rest of the sub is made from specially designed syntactic foam, similar to the sort of thing a surf board is made from.
It counterbalances the weight of the pilot’s compartment, which will have to keep the filmmaker safe from 1,000 atmospheres of pressure.
The submarine has been built and designed by an Australian team of engineers – many of whom have worked on James Cameron’s films. And a lot of elements of the craft come straight out of the movie industry.
Australian engineer Ron Allum, who co-designed the sub with Mr Cameron, is an expert at creating rigs that attach hi-tech cameras to submersibles.
But the Deepsea Challenger is the first submersible that he has built from scratch.
It is packed full of 3D cameras and huge lighting systems so that the director can capture the excitement of the voyage all the way to the bottom.