It’s the last place on Earth you’d want to be trapped, submerged 4000 metres under the ocean in a tiny submersible.

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The race for riches

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VIDEO The race for riches. Source: Sunday Night The race for riches

But this was the scary reality for China’s most experienced submariner, Fuen Tao, and his crew of deep-sea explorers.

In a rarely documented deep-sea dive, Fuen navigates the ocean floor 1200 kilometres off the coast of Africa in the tiny vessel Jiaolong.

He and his team are searching for valuable minerals on the ocean floor, competing with other explorers from around the world for the same prize.

The submersible is capable of travelling to depths of up to 11000 metres.

It’s a race for riches that deep-sea ecologist Professor David Booth is calling the ‘new gold rush’.

“Down in the deep ocean… down five, 10 thousand metres on the bottom, there’s incredible riches, in certain spots, of things like cobalt, zinc, gold,” Professor Booth told Sunday Night host Melissa Doyle.

Leading the race with their state-of-the-art technology is Fuen and his crew.

Their target on this mission is a football-field-sized section of the seabed.

They believe it could contain untold mineral riches - but it’s also incredibly dangerous.

Deep under the sea, scalding pillars of super-heated water shoots from under the Earth's crust.

In this part of the ocean, tectonic plates are constantly grinding up against each other, pushing up scalding jets of super-heated water, laden with toxins.

As Fuen navigates close to one volcanic smoke stack, the sub’s hydraulic arm jams.

While the crew scrambles to fix it, they fail to notice they’re drifting towards the searing hot pillars of water.

“That smoke can get to 400 degrees. It’s hot, really, really hot,” Australian journalist Rachael Thornton told Sunday Night.

Australian journalist Rachael Thornton has been given unprecedented access to China's exploration program.

Rachael has been given unprecedented access to China’s exploration program and said it was lucky the sub’s window wasn’t smashed by the heat and force of the water.

“[Fuen] threw the machine into reverse and got the hell out of there,” she said.

“Seconds, millimetres from death. Like any longer or any closer to that vent would have smashed the porthole and that’s it. Goners.”

The mission was aborted but on the way to the surface the situation went from bad to worse.

The submersible lost communication with the mother ship, leaving them even more vulnerable at the bottom of the sea.

They lost communication with the mother ship, leaving them even more vulnerable at the bottom of the sea.

Desperate, the crew tried to jettison ballast weights, but they didn’t release.

Finally, with no other option, Fuen tried the thrusters to get them clear of danger.

It was a slow trip to the surface, but they were happy to make it out unscathed.

The submersible wasn’t so lucky, sustaining severe scalding on the body and windows.

The Jiaolong suffered scalding to the body and windows.

But despite the close call, the rewards still outweigh the risks for deep-sea explorers.

“Deep-sea exploration is extremely risky,” Professor Booth told Sunday Night. “The pressures, the temperatures down there are huge.”

“The rewards now, I think, with especially some of these key rare elements are now worthwhile.”

“What will be found in the future will be even more remarkable.”

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