Tsunami hydrodynamics is the academic field and research area dedicated to the study of the physical processes governing the generation, propagation, and coastal interaction of tsunamis. It applies the principles of fluid mechanics to understand the complex behavior of these long-period ocean waves across various spatial and temporal scales. The field investigates wave initiation mechanisms, open-ocean evolution, and the highly non-linear processes of runup and inundation, employing theoretical analysis, numerical modeling, and physical experimentation. Its significance is paramount for advancing tsunami hazard assessment, developing effective early warning systems, and informing coastal mitigation planning.