Marina Exam Reviewer: When using a recording depth finder in the open ocean, what phenomena is most likely to produce a continuous trace that may not be from the actual ocean bottom?

Marina Exam Reviewer:

When using a recording depth finder in the open ocean, what phenomena is most likely to produce a continuous trace that may not be from the actual ocean bottom? 

A. Multiple returns reflected from the bottom to the surface and to the bottom again 
B. Echoes from schools of fish 
C. Poor placement of the transducer on the hull 
D. Echoes from a deep scattering layer  



Answer:      D. Echoes from a deep scattering layer 

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