At microwave frequencies, the sea cannot always be assumed to be a smooth, or mirror-like, reflecting surface. It is shown that when the sea is rough the reflected field will be a randomly fluctuating one, or will at least have a fluctuating component, even though the radiated signal is of constant amplitude and frequency. The central limit theorem of mathematical probability theory is used to derive the probability-density functions for the amplitude of the reflected signal, and for the amplitude of the combined reflected and direct-path signals. The possible practical significance of these results is discussed.