We consider the principles of radar sounding of the ocean surface using interferometers to reconstruct the level and velocity fields on the ocean surface. Likelihood functions are used to calculate the optimal algorithm of useful-signal isolation and the potential threshold sensitivity of interference synthetic-aperture radars with respect to the fields of the velocity and level of the ocean surface, depending on the instrumental, trajectory, and natural factors. The possibility to use space observations to reconstruct both small-scale fields of the altitude and the orbital velocity of energy-carrying wind waves and mesoscale fields, e.g., the field of altitudes of seismic gravity waves and the velocity field of geostrophic currents, is considered.