All SCUBA divers, whether beginning or advanced, should own their own mask, snorkel, fins, wetsuit and booties. You need a mask that fits perfectly to your own face, as well as other basic necessities that fit you well. You can rent most other equipment if you are a beginning SCUBA diver, but more advanced divers might want to invest in their own gear. Most divers do not ever own their own tanks; rather, they simply rent them from dive outfitters who are experienced with filling tanks.
BC (Buoyancy Compensator)
BC (Buoyancy Compensator) devices allow divers to control their buoyancy by adding and subtracting air to the vest. To descend and begin a dive, a diver empties her vest. She will then add or subtract air during the dive to maintain proper buoyancy. A diver wears the BC like a vest, and straps his tank into the BC on his back. Divers should try on a variety of BCs to find one that fits well.
A weight belt helps to reduce a diver's buoyancy. Wetsuits and BC vests tend to add buoyancy and can make it difficult for a diver to descend. Your size and weight will determine the amount of weight on your belt. You can add individual weights in a variety of increments until you reach the right amount.
Depth Gauges and Computers
A dive computer or gauge will tell you how deep you are, how much air you have consumed, and how long you have been underwater. Divers must pay attention to this information throughout the dive to make sure they do not go too deep or stay underwater too long. Monitoring air consumption is also important. The depth and length of a dive will also determine whether the diver needs to perform decompression stops during his ascent, and, if so, for how long. Gauges most often fit directly onto the tank in an integrated console, but some computers can also be worn like a watch on the diver's wrist.
While diving, you will breathe the air from your tank through a regulator. The regulator has a first and second stage. The first stage is attached directly to the tank and controls the air pressure and flow rate. The second stage is attached to the mouthpiece through which the diver breathes. Most regulators also have an additional, back up second stage for safety in case the first one fails.