Excuse my indulgence with things marine but put in perspective this is an awesome location on our planet.
Powerpoint presentation link
Challenger Deep got its name from the British survey ship Challenger II, which pinpointed the deep water off the Marianas Islands in 1951. Then in 1960, the US Navy sent the Trieste (a submersible - a mini-submarine designed to go really deep) down into the depths of the Marianas trench to see just how far they would go.
They touched bottom at 35,813 ft/10,915m. That means, while they were parked on the bottom in the bathyscaphe, they were almost seven miles/11km of water over their heads!
If you cut Mount Everest off at sea level and put it on the ocean bottom in the Challenger Deep, there would still be over a mile of water over the top of it!
The trench is host to thousands of species of invertebrates and fish including such oddities as the Angler Fish.
so called because it uses a bioluminescent (life light) protrusion to attract its prey.
The creatures which inhabit the Mariana Trench are all uniquely designed to survive in its extreme environment, but contrary to what one might readily assume, these life forms are not the result of evolution and adaptability - Quite the contrary, they are perhaps the most prehistoric life forms on the planet, some species, such as the Indians Ocean's deep-sea dweller the Coelacanth which has remained unchanged for millions of years.
The deepest dwelling fish known.
The "Viperfish".
What else may be down there is anyone's guess.