NOVELTY - The unit has a module for producing electricity from water currents, and including water current collecting device (30) and units to transform water current energy into electricity. The device has an envelope (20) and is movable with respect to the transformation units. The transformation units have a hermetic envelope (48) with a discoid electricity generator (70). Support units anchor the module on the bed of a river or the sea-beds.    USE - Used to be immersed in the bed of the sea or a river (claimed) at a high current zone for the production of electricity from the sea current or river.    ADVANTAGE - The presence of the discoid electricity generator permits to obtain a compact electricity production unit with improved performances. The collecting device is movable with respect to the energy transformation units so that the production unit is correctly positioned with respect to the water current direction, thus obtaining high energy efficiency and maintaining the efficiency at optimal value. The electricity producing module reduces the available power in case of a defect. The support units anchor the module on the bed of the river or the sea-beds, thereby enabling rapid installation and un-installation of the production unit. The electricity production unit can be raised to the surface to be put out of water and hoisted aboard a ship or a barge in order to facilitate maintenance operations on the sea or river without bring the production unit to the dock or ground. The electricity production unit therefore has a modular design that allows reduced immobilization of the unit during the maintenance operations. The hermetic envelope can made of composite material to avoid corrosion problem, while offering mechanical resistance, or any other type of material without deteriorating or modifying the operation principles of the production unit.    DESCRIPTION OF DRAWING(S) - The drawing shows a sectional view of an electricity producing module.    Envelope (20)    Water current collecting device (30)    Platform (35)    Hermetic envelope (48)    Discoid electricity generator (70)