A device (1) making it possible to convert the undulation and/or the oscillations of a liquid in which it is at least partially immersed into usable energy. The device (1) includes a float (3) guided by a guide device (2) anchored in the sea bed, with the aid of guide element (12) and including conversion element making it possible to convert the relative movements between the float (3) and the guide device (2) into usable energy such as electric energy.
