The ocean, a source and support of life on the earth, is one of the most complicated systems for scientists to simulate accurately. Numerical ocean models, running on the world’s most cutting-edge supercomputers, are the key tool for understanding and forecasting oceanic phenomena. Improving the accuracy of numerical models requires finer resolutions and incorporating more reasonable physical processes, and recent increases in computing power have enabled more detailed calculations on even finer grids. In this interdisciplinary dialogue we will address such questions as – what is state-of-the-art in numerical ocean modeling? And what are the current trends in model improvement? We will consider several applications of the surface wave-tide-circulation coupled numerical ocean model, such as nuclear radiation spread prediction following damage to the Fukushima Nuclear Power in 2011, and the rescue of lives at sea after boats capsized near Phuket in 2018. We will also discuss the history and challenges of numerical ocean model development and how ocean models and supercomputing relate to our everyday lives.