This Special Issue \"Nonlinear waves in the ocean\" is dedicated to various manifestations of the nonlinear behavior of ocean water waves of several different types, such as wind waves, rogue waves, tsunamis, internal waves and ship waves. It collects papers on these topics, mostly associated with the \"Nonlinear Waves\" Group (Nonlinear Processes in Geophysics Division) and the \"Sea and Ocean Hazards\" Group (Natural Hazard Division), presented at the EGU General Assembly 2011.