Title: How Scuba Works | HowStuffWorks
Headings: How Scuba Works
How Scuba Works
Wet Suits, Dry Suits, and Buoyancy Control
Scuba Breathing Apparatus
Diving Physics, Physiology and Hazards
Effects of Scuba Diving on the Body
Scuba: Additional Equipment
Scuba Training
Amateur levels

Content: Because the regulator is one of the most important pieces of equipment, many divers choose to purchase their own regulators (instead of rent) so that they can be confident that the regulator is in good working order and has been properly maintained. The final parts of the breathing apparatus are accessories that contain emergency or alternate air supplies. They include the following: Pony tanks - These are smaller cylinders that strap onto the main cylinder. Pony tanks contain air and have their own regulators. They provide enough air for many emergency situations, such as an ascent from a fairly deep depth. Spare air unit - The spare air unit has the regulator built directly into the on/off valve. It is lightweight and can be carried in the pocket of a BCD. It is designed to provide only enough air to allow you to ascend from