A beginner's guide to the equipment that makes diving possible.

One of my favorite moments in any Open-Water dive class is when my students come face-to-face with their first set of gear. Scuba is a gear-intensive sport because, let's face it, you're not designed to swim, see, stay warm or (most important) breathe underwater. If you want to explore what's beneath the surface you have to adapt, and dive gear allows you to do just that. To newcomers, the equipment can seem a little intimidating, but once you understand what each piece of gear does and how it works together, it quickly makes sense. I just love those “ah-ha!” moments when students literally put it all together for the first time. To help speed you along the learning curve, here is a handy guide to the essential gear all divers need.

(1) Dive Mask and Snorkel

Your dive mask creates a pocket of air in front of your eyes and nose so you can see clearly underwater and equalize the pressure on your ears and sinuses as you go deeper. Snorkels are breathing tubes that allow you to inhale and exhale when you're swimming facedown on the water's surface. Tip: The snorkel goes on the left side of your head and attaches to your mask strap.

(2) Regulator/Octopus

Your regulator lets you breathe underwater. It connects to your tank, delivering air to your mouth when you inhale. An octopus is a backup regulator. It usually has a longer hose and a bright yellow body so it's easy to find and can be used by others in an emergency. Tip: Both regulators should be routed to the diver's right side.

(3) BC/Power Inflator

BC stands for buoyancy compensator. It fits like a backpack, and supports the weight of your tank above water, but a BC's most important function is to help you control your position in the water column. By adding air to an internal bladder, you rise toward the surface; by venting air from it, you sink toward the bottom. The control buttons are part of the power inflator found at the end of the corrugated hose on the diver's left side. Tip: Quick-release buckles and adjustable straps make suiting up easier.

(4) SPG/Depth Gauge

Your instrument panel. SPG stands for submersible pressure gauge, and it tells how much air is left in your tank. The depth gauge tells you where you are in the water column. Tip: Letting your gauges drag or float freely is bad form. Clip them to your BC.

(5) Dive Computer

Your instrument panel on electricity. Computers monitor and display your depth, how long you've been under and how much longer you can safely stay. Some models will also keep track of how much air you have left. Tip: Computers may be used in conjunction with, or sometimes as a replacement for, traditional gauges.

(6) Scuba Fins

Scuba fins translate your kicks into smooth, efficient movement through a medium that's 800 times denser than air. Full-foot fins go on your bare feet; open-heel or adjustable fins require that you wear neoprene booties for a proper fit. Tip: Foot pockets should cradle your foot like a good pair of shoes--not too loose, not too tight.

(7) Wetsuit

Even warm water conducts heat away from your body 20 times faster than air. Wetsuits provide insulation against this cooling effect. Common options include 3mm-thick suits in both full and shorty (bare arms and legs) styles for warm water; full-length 5mm or 7mm fullsuits with a hood and gloves for cold water. Tip: A properly fitting wetsuit is snug all over, but not so tight that it restricts your movement or breathing.

Accessories

As you gain experience in diving, you may also use:

Dive lights: Specially sealed flashlights that bring out colors on the reef, allow you to peer inside reef crevices and even dive at night.

A dive knife: A tool, not a weapon. Used to cut lines, rope and monofilament.

Dive case: Hard-shell cases protect valuable gear in transit and seal shut to keep their contents dry in wet environments.