Breaking waves at the water surface is a striking example of turbulent mixing across a fluid interface. The impact of the jet generates turbulence, entrains air into the water and ejects droplets into the air. A fundamental understanding of the general multi-scale properties of the resulting multiphase turbulent flow is necessary to develop more accurate gas transfer or spray generation parameterizations. In this talk, I will discuss air entrainment, bubble statistics and the associated gas transfer by breaking waves in the ocean. The bubbles and wave breaking scales are studied through laboratory experiments and direct numerical simulations and the results are then up-scaled to the ocean using measurements of the wave and wave breaking statistics. This approach leads to a spectral model for bubble mediated gas transfer, as well as semi-empirical formulas relating wind speed and significant wave height, to air entrainment and gas transfer by breaking. Such parameterizations can then be used in coupled ocean-wave models.