Humans readily function within the narrow atmospheric envelope present at the
earth’s surface and are seldom concerned with survival requirements. Outside the
boundaries of the envelope, the environment is hostile and our existence depends
on our ability to counteract threatening forces. To function safely, divers must
understand the characteristics of the subsea environment and the techniques that
can be used to modify its effects. To accomplish this, a diver must have a basic
knowledge of physics—the science of matter and energy. Of particular importance
to a diver are the behavior of gases, the principles of buoyancy, and the properties
of heat, light, and sound.
