Abstract: An underwater breathing apparatus is provided for delivering air to a submerged diver. A manual pump supplies air under pressure to a reservoir bag for delivery to a diver through an air hose. Alternatively, the reservoir bag can be further connected by an air hose to a floatable variable-pressure reservoir bag that delivers air through an air hose to a submerged diver. In order to constantly maintain the air pressure in the reservoir bag in a preselected range, a pressure gauge is provided for the pump operator, who then pumps selectively to maintain the proper air pressure. The diver wears a breathing means having a flow restrictor/shut-off valve, a one-way inlet valve, and a one-way exhaust valve for exhalation. Additionally, an electric pump may be used either to replace the manual pump or as a back-up thereto.