We give an overview of an implementation of Reverse Time Migration (RTM) on heterogeneous multi-core hardware based on Graphics Processing Units (GPUs). We demonstrate the clear advantages of GPU-based hardware for RTM, not only in terms of performance for small to mid-scale problem sizes, but also for imaging 3D volumes on a scale appropriate to full Wide-Azimuth (WAZ) or Rich-Azimuth (RAZ) surveys in areas such as the Gulf of Mexico. We also point to advantages of GPU-based hardware in terms of energy efficiency.