Surface waves generated by submarine landslides are studied using a computational model based on Navier-Stokes equations. The volume of fluid (VOF) method is used to track the free surface and shoreline movements. A Renormalization Group (RNG) turbulence model and Detached Eddy Simulation (DES) multiscale model are used to simulate turbulence dissipation. The submarine landslide is simulated using a sliding mass. The three-dimensional numerical simulations are carried out for a freely falling wedge representing the landslide and subsequent wave generations. Simulation results are compared with the experimental data. Modeled illustrate the effect of slide geometry, computational grid, turbulence model parameters, and slide material density on the predicted wave characteristics and runup/rundown at various locations. Computed results also show the complex three-dimensional flow patterns in terms of the velocity field, shoreline evolution, and free-surface profiles. Predicted numerical results for time histories of free-surface fluctuations and the runup/rundown at various locations are in good agreement with the available experimental data.