Dive deep into the fascinating world of real-time computational fluid dynamics. We present details of our GPU-accelerated flow solver for the simulation of non-linear violent flows in marine and coastal engineering. The solver, the efficient lattice boltzmann environment elbe, is accelerated with recent NVIDIA graphics hardware and allows for three-dimensional simulations of complex flows in or near real-time. Details of the very efficient numerical back end, the pre- And postprocessing tools and the integrated OpenGL visualizer tool will be discussed. Moreover, several applications with marine relevance demonstrate that elbe can be considered as prototype for next-generation CFD tools for simulation-based design (SBD) and interactive flow field monitoring on commodity hardware.