A new two pass approach is presented based on a variation of backward ray tracing backward beam tracing. Advantages include its capability of rendering complex, hitherto unattainable, specular to diffuse phenomenon and its easy insertion into standard renderers. The algorithm is applied to aspects of the interaction of light with water. Within this context a variety of first generation effects, including shadowing and light scattering, are both rendered and animated. Results taken from the treatment of caustics within classical optics are included as they provide valuable insights into the precise nature of specular to diffuse transfer.