Effects of internal solitary waves on three-dimensional sound propagation and DOA estimation in the South China Sea

•1. We construct the processes of generating and propagating internal solitary waves (ISWs) in the South China Sea.•2. We use the Bellhop3D model to establish the 3D underwater sound field.•3. ISWs cause depressions in the iso-sonic surface, which lead to drastic fluctuations in sound rays and the horizontal refraction effect in the progress of sound propagation.•4. The internal wave increases the direction of arrival (DOA) estimation error and degrade sonar performance.•5. This study provides support for the 3D sound propagation mode and the arrangement of the sonar array in the internal wave environment.