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Scuba Diver

Scuba divers have to deal with intense water pressure when they dive down deep. Discover the effects of water pressure in this simple experiment.


What you need:

Foil tray, bendable drinking straw, paper clip, Play Doh or blue tack, empty 2 litre bottle, scissors


  1. Cut out a large piece from the foil tray. Draw your scuba diver on the piece and cut around. Make sure the scuba diver is small enough to fit through the opening of the bottle.

  2. Stretch out the drinking straw and bend over into a U shape, cut it so that it is around 3cm on each side of the U as shown.

  3. Hold the paper clip so that the two ends are pointing up. Hold the bent straw facing downwards and push one paperclip end inside one end of the straw and the other paper clip end into the other end of the straw as shown. This makes the diver’s scuba tank.

  4. Slide the ‘tank’ onto the diver so that the straw is pointing down.

  5. Squeeze a small amount of Play Doh around the diver’s feet.

  6. Fill a tall glass with water and test to see if the diver will float. If the diver sinks, check that the straw has no holes in it—if so replace it and continue.

  7. Fill water bottle to the very top and drop diver inside.

  8. Seal with the lid, place both hands around the bottle and squeeze. The diver will sink to the bottom. Release your grip and watch the diver rise back to the top.


Q: Hey Prof., Why does the diver sink when the bottle is squeezed?

A: As I mentioned before, it is all about pressure. The diver floats because air is captured inside the straw but when the bottle is squeezed the pressure forces water into the straw and makes the diver sink. When the pressure is released the water flows out of the straw and makes the diver buoyant again.

All of us go through times when we feel as if we can’t cope. That’s where that saying “You’re in over your head” comes from—just like our scuba diver in our experiment—we can feel like we’re sinking. The good news is that God is looking out for us. The Bible tells us that if you feel like that, “…give all your worries to him, because he cares for you” (1 Peter chapter 5, verse 7).

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