Reflection seismics has been intensively used for the last four decades by marine geologists and geophysicists for imaging Earth structures below the seafloor. Because their subject of interest is below the sea bottom, solid Earth scientists do not usually consider the seismic signal propagating in the water column and most often do not even record it, in order to save data storage space.
Two physical oceanographers, Gonella and Michon ,first reported internal waves revealed by reflection seismics in the northeastern Atlantic. Only recently, though, has the scientific community realized the importance of this issue, after Holbrook et al.  published reflection seismic sections of the water column off Newfoundland, Canada, showing reflectors related to the major oceanographic front between the Labrador Current and the North Atlantic Current.