—The present study investigates the interaction of steep waves with semi-circular breakwaterwith the complex plane's Cauchy boundary integral theorem.The boundary integral method is used totransform the calculation in fluid domain into its boundary alone.In the calculation the computation do-main is moved with the propagation of waves.A numerical solution is obtained for incident Stokes wavespassing the submerged obstacles.This method has been extended to the calculation of wave run-up on aslope for estimating wave overtopping.