A pumped storage power plant for a temporary reversible storage of energy, such as the energy available from wind power stations and/or photovoltaic systems that is fluctuating over time. The pumped storage power plant is designed as an underwater pumped storage power plant, wherein the ocean assumes the function of an upper storage basin and a pressure tank placed on the ocean floor serves as a lower storage basin. The storage of the electric energy takes place through pumping water out of the inside of the pressure tank against the hydrostatic water pressure on the ocean floor.