Deep offshore benthic habitats on the continental shelf are historically left unmapped due to the tyranny of depth and distance from shore. However, these deeper habitats on the shelf past 30m, called temperate mesophotic ecosystems (TMES), are likely far more widespread than previously thought and may support great biodiversity. In this study, data from autonomous underwater vehicles (AUVs), drop cameras, and towed cameras, were used to assess the distribution of mesophotic benthic habitats and taxonomic diversity across the southern coast of Australia. Moreover, waveform shaped reef features were analysed to see if they occurred more frequently along the ancient Pleistocene coastline at 90-120m water depth. We found that waveform shaped reef features were not just distributed across many areas of the southern Australian continental shelf, but were a main feature along the ancient shoreline. Additionally, the ancient shoreline reef features provided much premium hard substrate on the outer shelf and thus had much greater density of epifauna compared to surrounding habitats. These results support the growing consensus that the ancient Pleistocene shoreline of southern Australia and its associated benthic habitats is a key ecological asset.