On average its about 4 km meters deep, but the deepest part is called Challenger Deep, which is in the western part of the Pacific Ocean, a few hundred kilometers away from an island called Guam. It’s 11 km deep !!
It is named after the British ship called “Challenger II” which first examined the area in 1951 !
The ocean has lots of layers to it, and they have some really cool names. The top 200m are the epipelagic, or sunlit, zone where most marine mammals and fish live and where photosynthesis can occur.
Between 200m and 1000m is the mesopelagic, or twilight, zone where organisms like squid, swordfish, cuttlefish and wolffish live. Many organisms here glow in the dark by containing pouches with bioluminescent organisms.
Between 1000m to 4000m is the bathypelagic, or midnight, zone. Most animals that survive here live on the detritus that falls from the upper layers as a form of ‘marine snow’, or by preying on the other inhabitants that live here. The ocean is pitch black here, and is the home of giant squids and dumbo octopuses, with the occasional deep diving sperm whale.
From 4000m down to the ocean floor is the abyssopelagic, or lower midnight, zone. Very few creatures can survive the enormous pressures and cold here. You can find species of squid, basket starfish, swimming cucumbers, sea pig and sea spiders. On the ocean floor near volcanic fissures you can often find black smokers. These chimneys pump out superheated water and attract colonies of worms that feed on the minerals that escape.
In some parts of the world, especially near cracks in the crust of the earth, you can find deep trenches such as the Mariana Trench near Guam, that Nike mentioned. They have their own name, and form the hadopelagic zone. The waters here can be anything deeper than 6000m or 19,685ft! It is mostly unexplored. More people have visited the moon that the deepest points in the ocean!