Want to make a DIY bathyscope, or simple underwater viewer, with materials you probably already have at home? Explore life underwater with this simple tool that lets you see the magic of life below the surface.

A few weeks ago, we visited San Diego to see my sister. We hit up the beach for boogie boarding, digging in the sand, and dragging all the kelp out of the water and up onto the beach. My boys aren’t always fans of the beach, but this year really changed their tune. My older son, especially, fell in love with boogie boarding. Maybe next year we can get him on a surfboard.

The ocean is pretty amazing, and so is the incredible amount of life living under the water that we don’t often get to see and explore. Recently, my friend and RGK co-founder Jess took her youngsters to the beach for a family vacation. While they soaked up plenty of sun, they also added doses of science fun to their trip. There are so many ways to incorporate educational marine science into a family beach trip (without making it feel like a chore).

On her list of educational beach activities for kids, she included a suggestion to make a bathyscope with simple materials you likely already have at home. This stopped my scan. A bathyscope?! What the heck is a bathyscope? I have little marine science knowledge, so I did a bit of research to learn more.

What is a bathyscope?

A bathyscope, also called an aquascope, is a simple underwater viewer you can use from land or a boat to see life under the surface of a lake, river, ocean, or any body of water. When you submerge the bathyscope just under the surface of the water, it eliminates the glare on the water’s surface that typically prevents us from seeing the variety of life in the water.

You’ve probably seen a bathyscope before and just didn’t know that it had such a fancy name. A glass-bottom boat provides the same function as a bathyscope. Snorkeling and swimming goggles act like a bathyscope. Any transparent surface that you can submerge under the water’s surface and look through (provided it creates a layer of air between the water and your eyes) to see the world underwater offers the experience of looking through a bathyscope.

How do you make a simple bathyscope (or underwater viewer)?

You can easily make a simple bathyscope with materials you likely already have at home. At RGK, we’re big fans of reusing and repurposing materials you already have to eliminate waste and save money.

To make a bathyscope, follow this simple tutorial most kids can do on their own (or with a little assistance from an adult).

Materials to Make a Bathyscope:

Empty metal can or plastic cylinder container (like a yogurt tub)
Rubber band
Plastic Wrap
Can opener
Masking tape
Scissors

Instructions to Make a Bathyscope

If you use a can: Remove both ends of the can with a can opener. Be sure to pick a can that does not have a rounded bottom edge – those can be tricky to remove. I’ve used 15 oz fruit cans with success.
If you use a plastic cylinder container, remove the bottom of the container.
Cover the edges of the newly cut can or container with masking tape to avoid any contact with rough edges.
Place a piece of plastic wrap over one end of the can or container and hold it tightly in place with a rubber band.
Put the plastic-wrapped end of the can or container underwater and begin exploring.
Be sure to remind your investigators to not submerge the entire can in water, as the bathyscope won’t work with water on both sides of the plastic wrap.

Why does a bathyscope help us see better underwater?

I’m not an expert on how human eyes work. But at a basic level, human eyes are designed to see light as it refracts through the air. Thus, we can’t simply submerge our bare eyes underwater without changing how our eyes see light through the water instead of air. A bathyscope (or similar tool like goggles) allows us to submerge our “viewpoint” underwater without the water directly touching our eyes and changing how the eye focuses on the view.

You can buy a bathyscope, but we think it’s much more fun to make your own. It’s also a lot less expensive because it’s free!

If you make your own simple bathyscope, we’d love it if you could share it with us. Share it on Instagram and tag us @RaisingGlobalKidizens or send us an email with an image of your project. We love seeing our projects come to life in your home or classroom.

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