A fast approach for analysis of microwave scattering from wind-driven ocean surfaces is developed using the single integral equation with the method of moments.Triangular patches are employed to tightly model the random rough surfaces.The underlying algorithm is the FFT-based multilevel sparse-matrix canonical-grid method.A localized approximation method is introduced for the highly conductive seawater medium.Numerical examples are provided to demonstrate the merits of the proposed scheme.Simulation results are presented for ocean-like surfaces illuminated by microwave beams at L-band.