Abstract: A ship lock system having a ship lock interconnecting two bodies of water at different water levels. The system includes one or more underground hydroelectric pumped-storage units connected by one or more penstocks with the ship lock which serves as the upper reservoir to the pumped-storage units so that water can be drained from the ship lock through the penstocks to drive one or more reversible pump-turbines of the pumped-storage units which generates electrical energy, particularly during high demand hours for electrical energy. A lower reservoir adjacent to the pump-turbines is used to store the water which drives the turbines. The lowering of the water in the ship lock permits ships which entered the lock at the upper water level to leave the lock at the lower water level. By a pumping action, the pump-turbines can pump the water from the reservoir upward into the ship lock through the penstocks, particularly during periods of low power demand.