Ocean Floor Lesson for Kids

Instructor: Elizabeth Foster

Elizabeth has been involved with tutoring since high school and has a B.A. in Classics.

The ocean floor is a dark, mysterious place, and you will learn about it in this lesson. You will learn what it looks like and also what lives down there.

The Ocean Floor

From land, the ocean all looks the same. It's flat, blue, and honestly, it's kind of boring. But underneath that surface, there's a lot of stuff hidden at the bottom.

The bottom of the ocean is called the ocean floor. Just like the land above the surface, the ocean floor has mountains, volcanoes, deep trenches, and plants and animals. Let's learn about it now!

What Does the Ocean Floor Look Like?

To understand the ocean floor, you need to understand that the earth is like a great big onion with lots of layers. The inside layers are so hot that the rock is actually melted. On top of those melted rocks, there's a thin layer of solid rocks, called the crust. The ground you walk around on is part of the crust, and so is the bottom of the ocean.

The crust of the earth isn't just one layer of rock. It's made of big plates with cracks in between, kind of like a puzzle. The big plates of rock are floating back and forth on top of the melted rock underneath, and sometimes they get pushed into each other or pulled apart.

Mountains and Volcanoes

If two plates collide and both of them push upwards, they make a mountain range. One example is the mid-ocean ridge. The mid-ocean ridge is a huge chain of underwater mountains. Sometimes, melted rock from lower layers of the earth can flow up into the mountains to make underwater volcanoes.

This map shows the Atlantic Ocean. Darker blue means deeper water. The light blue line shows the mid-ocean ridge.
mid-ocean ridge


If two plates collide and one slides under the other, it creates deep trenches. One example is the Mariana Trench in the Pacific Ocean. It is the deepest spot in the world's oceans. If a giant picked up Mount Everest, the highest mountain on Earth, and dropped it into the Mariana Trench, the top of the mountain would still be more than a mile under the surface of the ocean.


Sometimes, the plates of rock slide past each other. Try sliding your hands against each other really slowly. Can you feel how they stick a little bit and then suddenly move? When that happens to two huge plates of rock, it can cause earthquakes on the ocean floor.

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