DIY Cartesian Diver

It might look like magic… but it’s actually science! Learn about the roles of pressure, density and volume on the physics of water in a DIY trick you can do at home.

Age Level: 10 – adult
Duration: 20 minutes
Supervision Requirements: May require assistance collecting appropriate materials


  • A plastic bottle with a screw-on lid (like a plastic soda bottle), with labels removed
  • A small eyedropper or pipette (don’t have one? use a bendy straw and a pair of scissors)
  • Small weights (pop tabs, paperclips, bobby pins, a small coin, dangly earrings — get creative!)
  • A rubber band, string, glue, or some other material for attaching weights to the diver (must be able to hold up underwater!)


Follow along with the video below to learn more about Cartesian divers and to build one yourself!