The deepest point on Earth
The Mariana Trench is located in the Pacific Ocean, just east of the 14 Mariana Islands near Japan.
The Mariana Trench is an arc-shaped valley extending generally northeast to southwest for 2,550km; its width is more than 50km.
The Mariana is one of many deepwater ocean trenches formed by the geologic process of subduction. This occurs when a plate topped by oceanic crust is subducted beneath another plate topped by oceanic crust.
The deepest point of the Mariana Trench is also the deepest point on Earth at around 11,000m (estimates vary). It is called the Challenger Deep and is located 340km south-west of Guam. It is named after the British exploration vessel HMS Challenger II which first attempted to measure the depth of the trench using echo sounding in 1951.
In 1960 a bathyscaphe called the Trieste, manned by Jaques Piccard (who's father invented the bathyscaphe) and Donald Walsh went to a depth of 10,915m in the Challenger Deep.
It is the deepest man has ever been.
The Mariana Trench is a very cold and highly pressurized environment - in fact the pressure is more than 1,000 greater than the pressure we feel at sea level.
Despite these deep sea inhospitable conditions, it is home to thousands of both everyday and highly unusual species of invertebrates and fish.
These include more common species such as sole and flounder, as well bizarre angler fish, which uses a bioluminescent (light produced by a living organism) protrusion to attract its prey.
If Mount Everest, the tallest point on earth at 8,850m, were set in the Mariana Trench, there would still be 2,183m of water left above it.