Fluid–structure interactions occurring between a wave train and an oscillating wave surge converter (OWSC) are studied in this paper using smoothed particle hydrodynamics (SPH). SPH is an alternative numerical method to conventional computational fluid dynamics for studying complex free surface flows. A new open multi-processing (OpenMP)-based parallel SPH code is developed and tested on a wave impacting an OWSC. An incompressible SPH (ISPH) method is implemented here to avoid spurious pressure oscillations, and an OpenMP approach is employed due to its relative ease of coding. The simulation results show good agreement with the experimental data. The performance of the new parallel SPH code is also reported for the water surge from a canonical dam break impinging on a tall square structure.