Sometimes called your "basic" gear, these three cover the minimum "adaptations" you need as a diver: seeing, breathing and swimming with your legs instead of your arms. When you put on scuba gear, you still need the mask so you can see and the fins for swimming. You still use the snorkel to save air at the surface, or in case you have to make a long swim (planned or unplanned) with an empty cylinder, especially if there's a current or chop. Except in a few instances, the snorkel is considered required recreational scuba equipment even though you can breathe from your scuba system.

In technical diving, you usually omit the snorkel because it causes more problems than it solves. However, tech divers do equip with snorkels in some circumstances, such as if they may end up a long way from a boat and have to wait for it to pick them up.

You'll want an exposure suit of some kind on all dives to protect you from heat loss and from abrasion. As covered in Chapter Four, water conducts heat from your body about 20times faster than air at the same temperature. Because of this, you can become dangerously chilled in water temperatures that would be comfortable in air. In very warm water you may not need thermal protection, but you still benefit by wearing something to protect you from incidental scrapes and stings.

Exposure suits include lightweight body suits (a.k.a. skin suits), wet suits and dry suits. You use body suits in warm water primarily for abrasion protection. Wet suits provide more insulation, making them suited to longer dives in warm water as well as cooler water diving. Dry suits provide the most insulation, enabling you to dive in cold waters, including at the Arctic or Antarctic. Besides suits, you'll usually wear some form of hand and foot protection, and in cooler water, a hood. Because tech dives can be two or three times longer than recreational dives, tech divers generally wear more insulation (almost never body suits) compared to recreational divers for the same temperature water.

SCUBA (Self Contained Underwater Breathing Apparatus Diving Equipment ) The standard recreational scuba system consists of three integrated components a high pressure compressed gas cylinder, a regulator and a Buoyancy Control Device (BCD). Each of these has subcomponents.

Your BCD is an inflatable jacket that you wear. It holds your scuba system together and allows you to control your buoyancy by adding or releasing air. By inflating or deflating the BCD, you can float easily at the surface or swim effortlessly over the bottom. Your BCD may also include your weight system. Tech divers use a similar scuba system, but with some important differences. The tech diver has two completely independent regulators and uses a wing-type BCD with a separate harness. The wing-type BCD sandwiches between the cylinders and the harness; tech BCDs may have two independent bladders and inflation/deflation systems.