Describe how sound waves are used to develop a map of the features of the seafloor.

Recordings are made with sensors recording particle motion at or near the surface of the ocean. Since the speed of sound in sea water is known, the travel time for sound reflections can be determined from the simple equation v = 2d/t where d is the distance down and back up, and t is the difference in time from the source time to the time a reflection is record. This can be rearranged to d = v*t/2.