Discussed in this paper is the deep scattering layer (DSL) observed during the experiment in the South China Sea in October 1983. The authors have investigated the acoustic characteristics of the DSL, such as the volume scattering strength of the water column, the thickness of the layer and the coefficient of the backscattering. Resonant scattering, presumably caused by the swimbladder of fishes, is responsible for the bulk of observed reverberation. In addition, the size of the swimbladder forming the acoustic scatter of the DSL is also estimated. Discussed in this paper is the deep scattering layer (DSL) observed during the experiment in the South China Sea in October 1983. The authors have investigated the acoustic characteristics of the DSL, such as the volume scattering strength of the water column, the thickness of the layer and the coefficient of the backscattering. Resonant scattering, presumably caused by the swimbladder of fishes, is responsible for the bulk of observed reverberation. In addition, the size of the swimbladder forming the acoustic scatter of the DSL is also estimated.