The sea surface is an almost perfect reflector. Energy travels upward from the seismic source toward the sea surface through the sea water at a velocity of approximately 1500 meters / second. Water has a density of about 1.025 grams/cc. It then hits the sea surface where the air above has an acoustic velocity of approximately 350 meters / second and a density of 0.0013 grams/cc. When these values are substituted into the Reflection Coefficient equation these give an value of -0.9994 below the sea surface, or an almost perfect reflector (with a sign reversal).
The ray paths for direct and ghost relectors are shown in the following figure.
