Underwater acoustics is widely applied among fields related to underwater investigation. This study aims to investigate the characteristics of sound propagation in waters off eastern Taiwan through sound propagation simulation, especially focusing on influences of the Gagua Ridge. Simulations are calculated through GBM (Gaussian Beam Model), and variables of the calculation include the locations, depths, azimuths, frequency of sound sources, base sediment, and sound speed profiles. Results show that SOFAR Channels, which are deep sound channels that allow sound energy to transmit within without much transmission loss, exist in all simulated areas. Sound from 1000m deep sources can all propagate in these channels for over 150km, the maximum range of simulation in this study. Some acoustic energy from 10m deep sources located closer to the Gagua Ridge show more significant transmission loss caused by the bathymetry, therefore being unable to propagate as far, while most others can propagate over 150km.