Diving equipment is expensive, but don't buy until it becomes cheaper than renting . . .

A new scuba rig runs $500 to $700. Start with a mask and snorkel, which costs about $20 and can be used anywhere. After you've passed a basic course in scuba and have rented equipment -- $30 to $50 -- several times you can judge how frequently you might dive. Many divers buy wet suit, fins, weight belt, mask and snorkel and rent the rest. Used equipment may reduce costs substantially, but a used tank, B-C or regulator should always be checked out by a professional shop. Here's the basic equipment: WET SUIT: Made of nylon-lined neoprene, it holds a layer of body-heated water against your skin to protect against the cold. A full suit -- gloves, boots, hood, jacket and pants -- is necessary for all deep-water dives in this area. $75 to $150. B-C: Short for buoyancy compensator, it's a vest that can be inflated orally or from the tank to adjust buoyancy so that you sink, hover or rise as desired. It counterbalances the weight belt. $40 to $200. WEIGHT BELT: It should hold just enough lead on your waist to take you down when the B-C is deflated. $10 to $20. TANK: By law it must be pressure-tested every five years and should be visually inspected annually. Common sizes hold 50, 72 or 80 cubic feet of air at more than 2,000 psi. A "J-valve" holds 300 to 600 psi in reserve in case you lose track or have an inaccurate pressure gauge. $80 to $200. REGULATOR: Reduces the air coming through the tank valve to a comfortable breathing pressure. $80 to $200. PRESSURE GAUGE: Tells you how much air is left. $40 to $60.