Abstract : The low-grazing-angle electromagnetic backscattering from small breaking water waves has been analyzed using computational electromagnetics (CEM) techniques. A new approach based on the multilevel fast multipole algorithm was implemented for 3-D surface crest scattering to supplement existing 2-D techniques. Multipath scattering between the wave crest and the front face can be modeled using physical optics on the face. A new method to model the specular reflection from jetting crests, termed extended gemetrical optics (EGO), was developed. The numerical calculations were shown to respond to the same measured surface features as experimental results, although polarization ratio differences demonstrate the importance or multipath scattering.