Abstract: Underwater drinking apparatus comprises a hollow body with a sidewall between proximal and distal ends, the proximal end of the housing including a fluid passageway functioning as a mouthpiece. A liquid-holding container removably connected to the body enables the liquid to flow from the container and into the hollow body. A piston slideably disposed in the body has a proximal end configured to seal off the fluid passageway. A spring within the body is operative to bias the piston toward the proximal end of the body to seal off the fluid passageway when not in use. The spring is preferably disposed between the distal end of the piston and an end cap threaded to the distal end of the body. A mechanism is coupled to the piston through the body providing a manually operated control enabling a user to move the piston against the spring.