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Information is the key to power in just about any endeavor. Underwater, information gives you confidence to explore your surroundings. Divers need to keep informed on four elements - pressure, depth, direction, and time - to know when to surface, and know when to dive. You can monitor these elements with a pressure gauge, depth gauge, dive watch, and compass.

PRESSURE - a standard piece of diver's gear is the submersible pressure gauge. A good pressure gauge has a greater capacity than the highest pressure at which it is normally used. This prevents inner components from being stressed to the limit. SPG's should also be shock resistant. Some gauges still use a system of gears inside that can 'skip teeth' if dropped on a boat deck. Pressure gauges also need two safety features; a way to vent air if internal parts leak, and a restrictive orifice to prevent rapid air loss if a hose bursts. Other desired features are read-in-the-dark luminous dials, fluorescent low air zone markings, and a modular system of consoles that lets you upgrade as your training and experience grows.

DEPTH - Depth gauges come in four different types; capillary, oil-filled, air-filled, and electronic. Each has different features and benefits, one of which will best fit your type of diving. Capillary gauges are merely a plastic straw closed at the top, where depth is indicated at the edge of a rising air bubble. They are only accurate in shallow depths but are extremely inexpensive. Oil Filled gauges provide linear indications of depth with equidistant dial markings. Linear scales can be more difficult to read, especially if the maximum depth of the gauge is over 200 feet. Still, the oil inside the gauge acts as a shock absorber, making these rugged and durable instruments. Air-filled gauges have the advantage of a non-linear scale so divers can more easily read depths in shallow ranges but still have an acceptably deep maximum depth. Air-filled gauges may also include other amenities such as maximum depth indicators and temperature gauges.

DIRECTION - Besides pressure, depth and time, finding your way to and from a dive site necessitates the aid of a compass. Some models have a needle, in some the entire dial rotates. Depending on your favorite navigation method, you may prefer a way to easily read numeric headings. An easy-to-turn bezel with numbers that won't scratch off is also important.

Because information quality is what makes it useful, choosing an instrument with which you are comfortable is very important. Graphic presentation of information, if done correctly, can be more easily understood making diving easier and more fun. Above all, when making a purchase be sure to pick an instrument system that won't become obsolete the next day. Choose correctly and you will be making an information investment that will greatly add to your confidence and control underwater.