How Deep Is The Ocean? The Zones Explained For Kids

The short answer

On average about 3.7 kilometers. At its deepest, the Challenger Deep in the Mariana Trench, about 10.9 kilometers: deep enough to hide Mount Everest with about 2 kilometers of water on top.

The Long Answer

Oceanographers split the ocean into zones by depth and by light:

Zone	Depth	What it is like
Sunlight	0 to 200 m	Enough light for plants and algae to grow.
Twilight	200 to 1,000 m	Dim blue light, not enough for plants.
Midnight	1,000 to 4,000 m	No sunlight at all. Anglerfish dangle lures lit by glowing bacteria.
Abyss	4,000 to 6,000 m	Near freezing, pitch black, the open seafloor.
Trenches	Below 6,000 m	The deepest places on Earth.

The Challenger Deep, in the Mariana Trench in the western Pacific near Guam, is about 10,935 meters down. The pressure at the bottom is more than 1,000 times the pressure at the surface.

Jacques Piccard and Don Walsh reached the bottom on 23 January 1960 in the bathyscaphe Trieste. James Cameron dived there alone in 2012.

Most of the seafloor still has not been mapped in detail: less than a third, about 29 percent, has.