  We report on the observation of surface gravity wave turbulence at scales
larger than the forcing ones in a large basin. In addition to the downscale
transfer usually reported in gravity wave turbulence, an upscale transfer is
observed, interpreted as the inverse cascade of weak turbulence theory. A
steady state is achieved when the inverse cascade reaches a scale in between
the forcing wavelength and the basin size, but far from the latter. This
inverse cascade saturation, which depends on the wave steepness, is probably
due to the emergence of nonlinear dissipative structures such as sharp-crested
waves.
