Jellyfish in a Bottle Science Experiment for Kids

I love this jellyfish in a bottle project because it’s three things in one. 1. It’s a science experiment. 2. It’s a lesson about the environment. 3. It’s a fun craft to make together.


  1. The science behind it: Air is lighter than water, and no matter which way you turn the bottle, the balloon will always rise to the top.
  2. Sea turtles eat jellyfish for food. Balloons and plastic bags in water look like jellyfish. According to researchers, half of all sea turtles have ingested plastic. By swallowing plastic, sea turtles can starve because their intestines get blocked or punctured.
  3. It’s a great summer craft because you recycle a water bottle into something else, and it allows you and your kids to spend time together.


  • Empty water bottle (I prefer the kind that is smooth all the way around.)
  • Self-adhesive craft foam (a.k.a., no messy glue)
  • Scissors
  • Balloon
  • Embroidery string
  • Blue food coloring
  • Water



Step 1: Blow a balloon up just a little. If you blow it up too much, you won’t be able to push it into the mouth of your water bottle. Tie the bottom in a knot and cut off the bottom of the balloon under the knot.

embroidery string

Step 2: Cut six to ten six-inch pieces of embroidery string.

balloon with embroidery string

Step 3: Tie the embroidery string around the knot of the balloon.

ballon in water bottle

Step 4: Carefully push the balloon into the mouth of the bottle and fill the bottle with water.

balloon in water bottle with blue water

Step 5: Add blue food coloring to the water. (You only need a drop or two.)

craft foam with scissors

Step 6: Cut sea shapes (sand, starfish, sea grass, fish, bubbles) out of self-adhesive craft foam.

craft foam on water bottle

Step 7: Stick the craft foam on the outside of the bottle.

Project complete.

jellyfish in water bottle craft

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