A Monte Carlo model has been developed for calculating the penetration of light into the ocean. For monochromatic light (490 nm) the spatial exact allocation of the scattered parts of underwater light is described in terms of the variation of particle content and the angle of light incidence. Based on this model, it is possible to generate complex spatiotemporal fluctuating light fields according to every possible shape of the water surface. By means of single gravity waves the focusing effect and its importance of radiance supply for water depths up to 100 m is discussed
