SCUBA QUIZ: Can You Guess the Right Pressure?

Do you remember what exactly happens with the pressure while scuba diving? Guess the density and volume at different depths! Some basic physics of SCUBA diving. Test your SCUBA knowledge here.

If you have done you PADI Open Water course or equivalent at another dive organization you probably have learned what happens to your body and the air in your tank at different depths. Air has weight and it presses on your body. The pressure is called atmosphere. Water is much more dense than air giving also pressure from the water when you go down.

With absolute pressure (ATA) you measure the total pressure of air and water. We have one atmosphere (1 ATA) pressure around us on land. Your dive instructor might have showed you the example of an air filled balloon or plastic bottle at various depths. Can you still fill-out the chart correctly?

Depth	Density	Volume
0 m / 0 ft	1 ATA	1
10 m / 33 ft	? ATA	?
20 meters / 66 ft	? ATA	?
30 meters / 99 ft	? ATA	?
40 meters / 132 ft	? ATA	?

HINT: The deeper you go the higher the pressure and the lower the volume.

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Answer

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Depth	Volume	Density
0 m / 0 ft	1 ATA	1
10 m / 33 ft	2 ATA	1/2
20 m / 66 ft	3 ATA	1/3
30 m / 99 ft	4 ATA	1/4
40 m / 132 ft	5 ATA	1/5

The pressure increases (gets bigger) when you descent (go down), the deeper the higher the pressure. Every 10 meters / 33 feet of water adds one atmosphere of pressure plus you already have the constant air pressure of one atmosphere. The higher the pressure the more the volume is compressed. If you double the pressure (x2) you have half the volume (/2) left.

This is part of the theory of Boyle, Boyle's law. Watch this video to learn more about pressure changes underwater: