AbstractWe investigate the relevance of Stokes waves for the propagation of ocean swell in the absence of strong currents. By providing estimates for the depth of the near-surface layer to which the main effects of a Stokes flow are confined, we show that wind-generated uniform wave trains can be modelled as Stokes waves over a fictitious flat bed, immersed in the water. Throughout the lower parts of this layer the deviations of the flow from a pure current are negligible.