Abstract: A drinking device for a diver includes a water container and a hand pump for pumping water to the diver's mouth. The hand pump includes a piston rod slidably engaged in a housing and two discs secured to the piston rod for separating the housing into an upper and a lower chambers. A passage is formed in the lower portion of the piston rod and has an aperture for communicating with a space formed between the discs. A sealing ring is slidably disposed in the space and may move upward to enclose the aperture for pumping the water in the lower chamber out of the housing. The sealing ring may also move downward to open the aperture for allowing the water in the upper chamber to flow into the lower chamber.