A hydroelectric power generator is capable of generating electrical power from a moving body of water. The power generator comprises a shell comprising a wall having interior and exterior surfaces, and an interior volume. A fixed gear is fixedly attached to the interior surface of the shell. A stationary shaft extends across the interior volume of the shell. A set of fins is attached to the exterior surface of the shell, and the fins are capable of rotating the shell about the stationary shaft from the force of the moving body of water. An electrical generator is mounted on the stationary shaft. The generator comprises a drive gear that engages the fixed gear to drive the electrical generator. An electrical connector transmits the generated electrical power to the external environment.