A mechanical or electromechanical timepiece including a watch case delimiting an internal volume, the watch case including a back delimiting the watch case at the bottom; a crystal closing the watch case at the top, the crystal defining a useful display aperture; a middle part connecting the back and the crystal to one another; a horological movement housed in the internal volume of the watch case; at least one hand for displaying information visible via a useful display aperture and rotated with respect to the watch case by the horological movement with at least one driving belt extending at least partially in the useful display aperture, the timepiece includes the internal volume of the watch case filled with a fluid wherein at least one driving belt is submerged, and wherein the driving belt is made of a material wherein the optical refractive index is equal or substantially equal to that of the fluid.