Abstract: A rotor having slidable blades is employed to efficiently produce electrical energy from underwater currents. The device includes a structure having four columns which rises from the seabed and supports a circular monorail system. A circular housing fits on top of the monorail. An interior and exterior gear rack on the monorail engage with motors within the circular housing. Four vertical rack structures are associated with the circular housing and may be driven up and down by another set of motors within the circular housing. Electrical generators are contained within a control house supported by the vertical rack structures. The rotor preferably comprises a housing having four slots which slidably receive four blades which reciprocate up and down as the rotor turns. An automatic control device can position the rotor vertically and horizontally so it impinges on the underwater current having the optimum velocity.