Abstract: An underground hydroelectric power plant for use adjacent to rivers, which utilizes an underground water tank connected to multiple underground penstocks. The said penstocks will carry water to underground turbines, which will operate generators for the generation of electricity. This electric energy will be transferred via underground cables to an offsite transformer. The water upon exiting the turbines will be led via an underground outlet pipe back to the river. This underground hydroelectric plant operates on the simple principle that a flowing body of water in a river must have a downward angle to it or the water would not flow and be stagnant, similar to a lake.