The efficiency of transport and exchange of energy, heat and mass is an important issue in nature. Turbulent transport dominates on the large scales in the Atmosphere and the Ocean, while diffusive transport mechanisms have most influence on small scales i.e. very close to the free water surface. There, the viscous boundary layer in water causes the main resistance of transport across the air/sea interface. Accurate knowledge about the flow field close to the surface is required in order to understand these mechanisms and the influence of the wave motion.