We’re exploring a part of the world that not much is known about—in fact, you could be one of the people who help us understand and learn more about this very important, and very large, part of our earth.

The land underneath the ocean is as varied and interesting as the terrain up on dry land—with mountains and canyons, plains and forests. (That’s right, forests! There are kelp forests where the kelp is as much as 150 feet tall!) In this episode, what’s known--and unknown--about the bottom of the ocean. How deep IS the deepest part of the ocean? And how was the Mariana Trench formed? We get answers from Jamie McMichael-Phillips and Vicki Ferrini of Seabed 2030, a global collaboration designed to map the sea floor, by 2030.

Resources

Download our learning guides: PDF | Google Slide | Transcript

Seabed 2030 

Visual: What Lurks In The Depths Of the Ocean? (CBC Kids)

“How deep is the deepest part of the ocean?” –Freya, 8, Wellington, New Zealand

The deepest part of the ocean is the Challenger Deep, 11,034 meters in the Mariana Trench. It’s about seven miles deep! How did the trench get so deep? 

The same processes that formed canyons and mountains on dry land also formed the depths of the ocean and the islands that peek above the water.

In the case of the Mariana Trench, it was formed by the process of subduction—when one tectonic plate slides under another. A tectonic plate is a gigantic piece of the earth’s crust and the next layer below that, called the upper mantle. These massive slabs of rock are constantly moving, but usually very slowly, so a lot of changes to the earth’s structure take place over a long time. But sometimes something like an earthquake can speed that process up.

A trench is formed when one plate slides or melts beneath another one.

The Mariana Trench is the deepest trench in the world—farther below sea level than Mount Everest, is tall!