Wave breaking and wave impact on maritime structures are difficult to model mathematically and numerically. The challenge is that nonlinear and breaking waves with their dynamic air-water interface need to be modelled accurately, including interactions with structures. We aim to progress nonlinear and breaking wave interactions on offshore wind turbines in two ways.Firstly, nonlinear unbroken waves are modelled in basins with wavemakers and with beaches to dampen the waves. Variational discontinuous Galerkin finite element methods (DGFEMs) are used to create stable simulations of potential flow water waves. Novel mathematics and numerics are proposed to couple these waves consistently to shallow water hydraulics at the beach, and advanced integrators are required to produce stable simulations of these wavemakers. Using two- (2D) and three-dimensional (3D) models, a good comparison can be made with existing and new measurements at MARIN's wave basins. We also propose a novel soliton-splash test to generate a freak-wave precisely in the target area for model wind turbines in MARIN's wave basin, to be simulated and created experimentally.In a related project, we propose a unified mathematical and numerical approach to simulate seas with intermittent wave breaking. For smooth waves when the phases are separated, it reduces to the previous DGFEM methodology, while in local regions of wave breaking an asymptotic mixture theory holds. A new discretization will be developed for this mixture theory model. It will be validated in 2D and in 3D. Our new calculations of breaking wave impact against fixed structures will be employed to obtain the pressure history at the foundation of offshore wind turbines. Subsequently, two-way hydro-elastic coupling will be devised to calculate deformations of the turbines. Wave-basin measurements will be used to validate our new, coupled hydro-elastic models of wave slamming. Outcomes will be employed in MARIN's consulting practice.