A first part of the chapter deals with wave refraction before a coast. Effects on wave heights and wave directions are dealt with analytically for the case of straight contour lines, and the numerical approach is explained in detail for arbitrary contour lines. The second part of the chapter is devoted to the problem of shoaling and set-down (or set-up) of waves on a current. The way to calculate the current effect on wavelength and wave height is shown. A FORTRAN program is given and applied to a worked example of calculation of the Froude–Krylov force on a submerged tunnel across a strait with waves and current.