High Performance Computing (HPC) represents a crucial resource for Computational Mechanics in supporting many professional activities: design and verification of engineering works and products; implementation of safety actions to preserve human health, public and private goods from natural and anthropic hazards; land-use management based on scenario simulations; decommissioning, remediation and restoration of industrial/power sites;... Among the Computational Fluid Dynamics (CFD) numerical methods, Smoothed Particle Hydrodynamics (SPH) is a mesh-less technique particularly suitable to represent 3D non-stationary free-surface and multi-phase flows including fluid-structure interactions and granular flows. The seminar describes the reference methods (i.e. mathematical models, numerical formulations) and the HPC applications of the SPH FOSS (Free/Libre and Open-Source Software) code SPHERA (RSE SpA) on the following topics: floods; landslides; fuel sloshing tanks; sediment removal from water reservoirs; sea surface waves. The multi-physics numerical schemes of the code are highlighted with emphasis on fluid-structure interactions and the transport of solid bodies and granular material.