As the capacity of computers continues to increase, large-scale numerical simulations have become a powerful tool to analyse complex physical phenomena. Tsunami simulations are currently widely used for a variety of purposes, including tsunami hazard mapping, estimating damage patterns or evaluating forces on coastal structures. In many cases a two-dimensional tsunami simulation is employed, which generally consists of estimating the initial conditions around the source of the wave and then calculating its propagation and inundation based on the governing equations and bathymetry/topography data. Although there are several ways to conduct such simulations, the present chapter will describe the basic manner in which they can be done.