The Ocean Floor

Contributor: Meghan Vestal. Lesson ID: 11524

The ocean is pretty deep, isn't it? It's hard to imagine that is has a floor! It does, and there are a lot of interesting features down there, even volcanos! Get ready to build an edible ocean floor!


Earth Science

learning style
Kinesthetic, Visual
personality style
Lion, Beaver
Grade Level
Middle School (6-8)
Lesson Type
Dig Deeper

Lesson Plan - Get It!

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  • What do you call an underwater volcano?
  • Can you imagine a red-hot volcano under the water?

West Mata submarine volcano

Image by NOOAA, via Wikimdeia Commons, is in the public domain.

There are hills, mountains, valleys, and volcanos on land.

  • Did you know these things also exist on the ocean floor?

The ocean floor has a unique surface that is also a part of the Earth's crust.

  • Do you know the names of any underwater landforms?

Share what you already know with your teacher or parent.

Now, look at the image below to see all the underwater features and landforms that you need to know:

oceanic basin

  • What features are unfamiliar to you?
  • Can you tell what each feature is by looking at the image?

Review this list of terms to learn more about each of the features that make up the ocean floor:

Continental shelf

The continental shelf is part of the continental crust. It is the part of a continent that is underwater.

The continental shelf is located in shallow water. The continental shelf extends roughly 330 to 600 feet from land and gradually slopes out to sea.

If you have stepped off the sand on a beach and into ocean water, you have walked on the continental shelf!

Continental slope

The continental slope borders the continental shelf. Like the continental shelf, the continental slope gradually slopes out to sea, causing the water to get deeper.

The continental slope's decline is much steeper than the continental shelf, and can even appear to drop off completely in some places. The continental slope is about 200,000 miles long and ranges from 330 to 10,500 feet deep.

Continental rise

Following the continental slope is the continental rise. In these places, ocean and continental sediments build up to form large gently-sloping masses that rise up in some places.

Mid-ocean ridge

Mid-ocean ridges, also called oceanic ridges, are chains of mountains on the ocean floor. Often these mountains are volcanic. About 50,000 miles of oceanic ridges make up the ocean floor.


Oceanic trenches are formed by moving plates that are a part of the Earth's crust. These moving plates are called tectonic plates.

As these plates move, deep valleys can form underwater. These underwater valleys are called trenches and range in depth from 24,000 to 36,000 feet.

Trenches are mostly unexplored territory because their depth prevents scientists from visiting them.


Seamounts are ocean volcanos.


Guyots are flattop ocean volcanos.

Review what you have just learned:

  1. Take out a piece of paper and coloring materials.
  2. Draw and label your own picture of the ocean floor. Try to make your drawing different from the one pictured above.
  3. Make sure to include each of the underwater features listed above.

When you are finished, share your drawing with your teacher or parent.

  • Which parts of the ocean floor do you find most interesting?

Tell your teacher or parent. Then, move onto the next section to practice memorizing each of these terms.

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