A hydroelectric device, for the production of electricity in an aquatic environment with currents, includes a frame supporting a rotating member having a number of bearing surfaces that cooperate with the currents to generate a rotation of the rotating member. An electromechanical device produces an electrical current from the rotation. The hydroelectric device also includes a device for adjusting the position of the rotating member with reference to the surface of the aquatic environment. The latter device includes a tank having a variable opening positionable under the surface of the aquatic environment for modifying the water filling rate of the tank. The rotating member may be mounted on the frame by means of a shaft extending along a perpendicular direction to the currents, which facilitates the coupling thereof to one or two similar hydroelectric device shafts arranged at either end of the first, in alignment.