A bicycle is an operating system. It has handlebars, a seat, pedals, gears, a chain and lots of other components that perhaps haven't been mentioned. In order to get the best experience with the bicycle, all of the components should be present and operational. A bicycle can perhaps be operated with only one pedal or without the seat, but not efficiently and comfortably.

Diving equipment is also an operating system. This operating system uses variety of components:

·  Mask, Snorkel, Fins
·  Buoyancy Control Device, Weight Belt and Weights
·  Environmental Protection
·  Regulator, Gauges/Computer

Mask - your picture window to the underwater world. A mask requires a proper fit more than anything else. Most masks are made of clear silicone rubber and a shatter-proof lens. Optical correction is available in a variety of way: gas permeable contact lenses, replaceable lenses, or lenses created to your exact prescription. If you need glasses to drive, you need glasses to dive. Color correcting lenses are also available.

Snorkel - comfortable fit in the mouth, large enough bore to allow adequate air exchange. Water drain valves increase personal comfort.

Fins - several types available. Strap fins are designed with a foot pocket large enough to accept the protective dive boot. The fin should be designed to develop sufficient propulsion for the diver while underwater wearing scuba equipment. The Force Fin is a unique strap fin design that is gaining popularity. Full foot fins are worn without a boot and are more frequently associated with snorkeling.

Buoyancy compensator - this is one of the most critical pieces of equipment a diver can own. Proper size & fit of the BC directly affects a divers comfort in the water. The best designs have efficient adjustment harnesses rather than just using the bladder for support. Many designs are universal in nature, but some are specifically designed for women. The best rule of thumb is to look for an internal harness that secures the tank to the divers body and shifts the weight off the shoulders down toward the lower back like a hikers pack. This feature helps a diver maintain balance on land and, more importantly, underwater.

Weight belt - many destinations make weight belts available along with weight. Your own belt (leave your weights at home) will probably be in better condition and should be sized to fit you.

Environmental protection - this set of equipment includes wet and dry suits, polartec and skin suits, boots, gloves, and hoods - Like the BC, environmental protection equipments performance efficiency is dependent upon proper fit. Labor intensive features such as butt glued seams in wet suits add heat retention and durability as well as cost, but are well worth the additional expense. Polartec suits, lycra suits, and polyolefin skin suits are useful in warm water because they have no buoyancy change. This translates to less weight needed to dive. These suits can also be used as cold water suit liners. Colder water diving environments require thicker wet suits or dry suits.

Regulators, Gauges/Computer - Most divers will require a balanced first stage and a downstream second stage. This means that the regulator should function about the same throughout the dive. A major regulator consideration is the type of diving planned. More aggressive diving (deeper than 60 feet, presence of current, or greater physical effort) dictates the need for a higher performance regulator. This is true of physically large persons as well. Higher performance regulators offer easy, effortless breathing and lots of air. These regulators frequently offer creature comforts such as lighter, smaller 2nd stages. Persons who are physically smaller or less aggressive divers (not deeper than 60 feet, in strong currents or other physically challenging conditions) probably may not need a high performance regulator but might want the additional features.