Equipment
Mask
Keeps water out of your eyes and allows you to see clearly.
Fins
Allow you to swim efficiently without using your arms.
Buoyancy Control Device (BCD)
Jacket that forms the heart of all your gear. You can inflate or deflate a BCD in order to allow you to sink, hover "weightlessly", or float on the surface.
Cylinder
Stores compressed air for you to use while underwater. The air supply typically lasts 30 minutes to an an hour depending different variables such as depth and activity.
Regulator
Delivers air from the cylinder at the correct pressure for you to inhale.
Alternate Air Source
A second mouthpiece connected to the cylinder to share air with a second diver.
Exposure Suit
Wet suits and dry suits keep you and protect you from the environment. Wet suits trap a small amount of water between the suit and the your skin, while dry suits keep you dry so you can remain warm in the coldest environments.
Submersible Pressure Gauge(SPG)
More commonly referred to as an air gauge, the SPG constantly tells you how much air you have remaining in the cylinder.
Compass
A regular compass that is used for underwater navigation.
Dive Computer
Used to track depth and time in order to tell you much time you can spend at depth. More advanced computers have a built in air gauge.