How do satellites determine the terrain of ocean floor?

Satellites cannot directly measure the underwater topography as radar signals used in Satellite altimetry cannot penetrate through the water body. But oceanfloor topography can be determined indirectly by the satellite altimetry from sea-surface height measurements as the sea surface height is affected by the variations in seafloor topography. Over the seamounts and oceanic ridges, due to the shallowness of the ocean floor, the water height is low resulting in the presence of sea-surface height lows (SSHL). Over deep-sea trenches and abyssal plains, due to the deepness of the ocean floor, the water height is comparatively high forming sea-surface height highs (SSHH). Thus SSH data acquired through altimetry can provide crucial information about the oceanfloor topography. To determine the ocean depths with maximum precision, the seafloor topography data acquired through satellite altimetry with other oceanographic and geophysical data are combined and then analyzed.