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Science Experiments

Bottle Diver Science Experiment – A Scuba Diver in a Bottle

This experiment takes a few minutes to set up, but once done you can do the experiment over and over. Kids will enjoyed taking turns making the scuba diver move up and down in the bottle.

Bottle Diver Science Experiment

JUMP TO SECTION: Instructions | Video Tutorial | How it Works

Supplies Needed

  • Empty Plastic Two Liter Bottle
  • Drinking Straw
  • Small Paper Clip
  • Play-dough or Reusable Adhesive Putty
  • Thick Foil (I used a Foil Pan)
  • Scissors
  • Water

Bottle Diver Science Experiment Instructions

Step 1 – Cut out your diver using the same shape and size indicated above. I lightly sketched my diver on my foil before I cut him out. Note: That is a small paper clip. The diver should be approximated an inch and a half tall.

Helpful Tip: Download the Template for the Bottle Diver Here

Step 2 – Cut the straw and position it on the paper-clip as shown above.  Each end should be secured by the ends of the paper clip.

Step 3 – Slowly slide the straw onto the diver as shown above. The diver should look like he’s wearing a scuba tank. Then place a small piece of play-dough or putty on the diver’s feet.

Step 4 – Fill a glass with water and put the diver in. This is to test to make sure it floats. It should float as shown above. If it doesn’t float, your straw may have a hole in it. Try again with a new straw.

Step 5 – Fill the two-liter bottle with water. Make sure to fill it to the top, otherwise, the experiment won’t work.  Carefully place the diver into the bottle and screw on the lid.

Bottle Diver Science Experiment

Step 6 – What do you think will happen when you squeeze the bottle? What about when you stop squeezing the bottle. Write down your hypothesis (prediction) and try it out and observe what happens.

Do you know why then you squeeze the bottle the diver sinks to the bottom and when you stop squeezing the diver floats back to the top.

Find out the answer in the how does this experiment work section below.

Video Tutorial

Bottle Scuba Diver Science Experiment Step by Step Instructional Video

How Does the Science Experiment Work

This experiment is also referred to as the Cartesian Diver Experiment and it is a simple and fun way to teach kids about density and how it impacts whether an object will sink or float.

Density is a measure of the mass per unit volume of a substance. Water has a density of 1 g/mL (g/cm3). Objects will float in water if their density is less than 1 g/mL. Objects will sink in water if their density is greater than 1 g/mL.

When you first put the diver into the bottle, the combined density of the diver, straw, paperclip and playdough is slightly less than the density of water, so it floats. A small bubble of air gets trapped in the straw when you put the diver in the bottle. When you squeeze the bottle, you increase the pressure of the water in the bottle, so water is forced up into the straw compressing the air bubble in the straw. As the air bubble gets smaller, the density of the diver increases and the diver begins to sink. When you release the bottle, the pressure lessens and the water moves back out of the straw. The air bubble in the straw returns to its original size causing the diver to become less dense and float back to the top of the bottle.

Other Ideas to Try

Try this experiment in different ways – try it with cold water in the bottle and then try it with warm water in the bottle. Does temperature affect the density of the diver?

I hope you enjoyed the experiment. Here are some printable instructions:

Bottle Diver Science Experiment

Bottle Diver Science Experiment

Materials

  • Empty Plastic Two Liter Bottle
  • Drinking Straw
  • Small Paper Clip
  • Play-dough or Reusable Adhesive Putty
  • Thick Tin Foil (I used a Tin Foil Pan)
  • Scissors
  • Water

Instructions

  1. Cut out your diver using the same shape and size indicated above. I lightly sketched my diver on my foil before I cut him out. Note: That is a small paper clip. The diver should be approximated an inch and a half tall.
  2. Cut the straw and position it on the paper-clip as show above. Each end should be secured by the ends of the paper clip.
  3. Slowly slide the straw onto the diver as show above. The diver should look like he’s wearing a scuba tank.
  4. Place a small piece of play-dough or putty on the diver’s feet.
  5. Fill a glass with water and put the diver in. This is to test to make sure it floats. It should float as shown above. If it doesn’t float, you’re straw may have a hole in it. Try again with a new straw.
  6. Fill the two liter bottle with water. Make sure to fill it to the top, otherwise the experiment won’t work. Carefully place the diver into the bottle and screw on the lid
  7. Squeeze the bottle and watch as the diver sinks to the bottle. Stop squeezing and he will float back to the top.
© Cool Science Experiments HQ
Bottle Diver Science Experiment Steps

 


8 Comments

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Reader Interactions

Comments

  1. Abby says

    February 15, 2016 at 2:45 pm

    I’m looking for the pattern for the diver and I can’t find it on the website. Could you direct me to it or email it to me?

    Thanks so much!

    Reply
    • Danielle says

      February 18, 2016 at 1:43 pm

      Abby,

      Thanks for asking and for pointing out that it was difficult to find. Here is a link to download the template. I’ve also updated the instructions to make it easier to find.

      Bottle Diver Template

      Have fun with the experiment!

      Danielle

      Reply
  2. Dawn says

    June 6, 2016 at 8:45 am

    I’m having trouble getting the play dough to stick. Does blue tack or something else work better?

    Reply
    • Danielle says

      June 6, 2016 at 1:21 pm

      Hi Dawn,

      I’d first try wetting the play dough just a little bit and then pressing it on the diver. That may do the trick. If not, blue tack should work or you could try silly putty.

      Hope that helps!

      Danielle

      Reply
  3. Gaya says

    March 10, 2017 at 2:23 am

    HI Danielle! Actually i am looking for cool experiments about density.But in ur web all is like kids experiments.So can u give me suggestions some cool experiments with density?I am asking u because i have a competition to go through,so i really want to impress the judges.Please help me,Danielle

    Reply
    • Danielle says

      March 14, 2017 at 9:42 am

      Gaya,

      Here is a link to an list of simple experiments related to density. I hope it helps!

      Danielle

      Reply
  4. Elijah says

    April 12, 2017 at 7:59 pm

    I can’y get my scuba diver to go up it just sinks when I put it in!

    Reply
    • Sam Jara says

      October 24, 2017 at 9:42 pm

      Maybe your scuba diver is too heavy, try removing some Play-Doh

      Reply

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