How deep is the ocean?

Ocean depth is divided into zones: littoral, bathyal, abyssal and hadal. The deepest part of the ocean, the hadal zone, is anywhere deeper than six kilometres.

What is the average depth of the ocean?

The ocean has an average depth of approximately 3.7 kilometres (or 2.3 miles). A calculation from satellite measurements in 2010 put the average depth at 3,682 metres (12,080 feet). However, at the time only about 10% of Earth's seafloor had been mapped to high resolution, so this figure is only an estimate.

How deep is the deepest part of the ocean?

Challenger Deep, in the Mariana Trench, is the deepest point in the ocean known so far, at approximately 11 kilometres - deeper than Mount Everest is tall.

The Mariana Trench is 2,500 kilometres long, running north to south in a crescent-shape. It's located in the western Pacific Ocean near the Mariana Islands.

The trench's depth was first measured during the Challenger expedition in 1875. But it wasn't until the 1950s that scientists recorded its deepest depth. 

Why are oceans so deep?

The extreme depth of the Mariana Trench and other oceanic trenches is caused by subduction. This is where on the boundary of two converging tectonic plates, one descends down into Earth's mantle, creating a deep trough.