The Mariana Trench in the western Pacific is the deepest known place on Earth. The bottom sits nearly 11km below the surface of the ocean, the pressure of the water is roughly the same as the weight of 48 Boeing 747s and anyone journeying down won’t have seen natural light for 10,000m.
But that’s not stopped James Cameron who has become the first solo diver to reach the sea bed. And if you’re struggling to comprehend exactly how deep it is, there’s a handy video and graphic at the bottom.
He made the solo descent in a sub named "Deepsea Challenger", taking over two hours to reach the bottom where he spent more than three hours exploring the ocean floor. It's only the second manned expedition to the ocean's deepest depths - the first took place in 1960 when US Navy Lt Don Walsh and Swiss oceanographer Jacques Piccard went down, but there landing kicked up silt making visibility very poor.
As he reached the bottom of the Mariana Trench Cameron sent out a Tweet reading: "Just arrived at the ocean's deepest pt. Hitting bottom never felt so good. Can't wait to share what I'm seeing w/ you."
Cameron's craft was kitted out with cameras and lights to film the whole thing and he intends to release a documentary.
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."
Images: Nat Geo/Wiki Commons