Aqua Vision has been contracted by the Belgian government to implement a wave model called SWASH. This open-source numerical model can simulate short wave propagation and dissipation in shallow coastal areas. For this project, it is used to simulate wave penetration into several Belgian harbours along the North Sea coast. Wave measurements inside and outside the harbours are used to calibrate and validate the models. The final result is a model which can reproduce wave parameters within the harbors under different circumstances such as varying water levels, varying offshore wave heights, and changes in the geometry of the harbour entrance.