Technical (tec) diving involves diving beyond normal recreational scuba diving limits. Participating in tec diving requires additional experience, training and (of course) equipment. In recreational diving you use one scuba tank, but tec divers typically wear twin cylinders or closed-circuit rebreathers (CCRs), plus one or more additional tanks, each with different gas blends. They usually have two or more completely independent regulators and dive computers, as well as other dive gear backups. Visit your PADI Dive Center or Resort to get advice about tec diving gear, but here is what a typical tec diver might use.