Hollywood director James Cameron has plunged nearly 11km (seven miles) down to the deepest place in the ocean, the Mariana Trench in the western Pacific.
He made the descent alone in a prototype submarine called "Deepsea Challenger", taking around two hours to reach the bottom.
Once he reached a depth of 10,898 metres (35,756 ft), his first words up to the suface were: "All systems OK."
His craft is kitted out with cameras and lights so he can film the deep.
This is only the second manned expedition to the ocean's deepest depths - the first took place in 1960.
The earlier descent was made by US Navy Lt Don Walsh and Swiss oceanographer Jacques Piccard.
They spent about 20 minutes on the ocean floor but their landing kicked up silt, meaning their view was obscured.
Before the dive, the Titanic director told the BBC, that making the descent was "the fulfilment of a dream".
He said: "I grew up on a steady diet of science fiction at a time when people were living a science fiction reality.
"People were going to the Moon, and Cousteau was exploring the ocean. And that's what I grew up with, what I valued from my childhood."
Deep ambition
Cameron's last words before his descent were: "Release, release, release."
The Deepsea Challenger was made in Australia.
Cameron spent the last few years working in secret with his team of engineers to design and build the craft, which weighs 11 tonnes and is more than 7m (23ft) long.
He describes it as a "vertical torpedo" that slices through the water allowing him a speedy descent.
The tiny compartment that the filmmaker sits in is made from thick steel, which is able to resist the 1,000 atmosphere of pressure he will experience at full ocean depth.
The rest of the vertical column is made from syntactic foam, giving it enough buoyancy to float back up.
The sub has so many lights and cameras that it is like an underwater TV studio - with Mr Cameron able to direct and film the action from within. He intends to release a documentary.
It also has robotic arms, allowing him to collect samples of rocks and soils, and a team of researchers are working alongside the director to identify any new species. He says that science is key to his mission.
If successful, Mr Cameron's multi-million-dollar expedition, which has been financed by the filmmaker himself, Rolex and National Geographic, is the first manned effort to the deep for half a Century.
In 1960, Don Walsh, a former US navy lieutenant, and Swiss oceanographer Jacques Piccard made the first historic dive in a bathyscaphe called the Trieste.
http://www.bbc.co.uk/news/science-environment-17503395 
