Ocean Diver

a red and orange exhibit table with a white and blue information panel on top. On the table top sits a clear plastic water bottle with a black top and bottom.

Pressure causes bubbles to contract and items to sink due to lower buoyancy.

How it works

Squeeze a water bottle to observe changes in bubble density, floating and sinking.

Things to try or ask around the exhibit

Can you make the ‘diver’ sink by squeezing the bottle?

Background

The diver has an air bubble trapped inside it. When you squeeze the bottle, the diver’s air bubble is squashed (making the diver ‘heavier’) and the diver sinks.

Any object in water pushes water out of the way, and the water pushes back. Something floats if the downwards pull of its weight is less than the upwards push of the water.

Weight can be changed by inflating or deflating the air bubble, to make an object less or more dense than the surrounding water.

Finding the science in your world

Fish and submarines hover underwater by using gas bladders or air tanks. When the fish's swim bladder inflates with air, the fish is less dense relative to the water and it is able to swim towards the surface. When the swim bladder shrinks, the fish becomes more dense relative to the surrounding water, so it can dive deeper into the ocean.