Abstract: A benchmark analytical solution for three-dimensional sound propagation excited by a point source in a penetrable wedge-shaped ocean is presented in this paper. This analytical solution presented in this paper is based on the method of source images, and it applies to the acoustic fields in both water and the bottom. For the acoustic field in water, only acoustic reflection needs to be considered. However, for the acoustic field in the bottom, both acoustic reflection and acoustic refraction need to be considered. Due to the complexity of spherical wave reflection and refraction on the interface of two media, the spherical wave radiated from each source image is expressed in terms of plane waves. Therefore, the analytical solution in the whole sea area can be obtained by using the plane wave reflection and refraction principles. The new solution is accurate throughout both water and the bottom, including the normally difficult modal cutoff regions, where energy propagates through the wedge at grazing angles close to the critical grazing angle; and so the analytical solution could be as a benchmark to validate the accuracy of three-dimensional numerical models. Consequently this analytical solution is also validated through a benchmark penetrable wedge problem.