Course Outline

Diving requires you to pay attention to some things that fall into the diving physics category. Don’t be alarmed. You do not need a PhD in quantum mechanics to understand what is required in this section. All that’s needed is familiarization with a couple of ratios and being able to work with a formula or two—and these you can bookmark or write down in the back of your logbook.

And of course, there is an extremely good reason for you to pay attention to and understand diving physics: your safety.

When you are underwater, hearing, breathing, seeing, feeling, and moving are not the same as when you are above water. And because of this, you need to pay attention, be aware, and be careful.

For instance, it is important to pay attention to the following:

  • Water density causes drag and effectively decreases our ability to move freely.
  • Colors appear different because certain wavelengths of light are absorbed by water, even clear water.
  • Another visual change is that objects seem a little larger underwater, so making a grab for something like an anchor line can leave you empty-handed!
  • Water is a much better conductor of heat than air. As a result, you’ll lose heat much more quickly in water.
  • Most importantly, at sea level, water weighs about 800 times more than air. Therefore, as you descend underwater, you are quickly subjected to increased pressure. This greatly affects what happens inside a scuba diver's body—your body.
  • Lastly, things such as dive gear seem to weigh less underwater, and of course, this has some advantages. However, take those first couple of steps slowly after your dive and when you're back on the surface. You're heavier than you think.

You do not need to understand every part of every physics law or equation, but you must understand how physics can affect you and your body when you are underwater.

The following are the course objectives:

  • Explain some of the physical effects on divers underwater
  • Describe the three states of buoyancy
  • Explain pressure, volume, and density relationships
  • Describe the effects on light and sound underwater
  • Explain how to calculate surface air consumption rates (SAC)
  • Explain why an important part of pre-dive planning is to calculate air consumption rates and project how long a diver's gas supply will last
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