In a drifting ice pack, the mean drag depends upon the amplitude of oscillations present, and it reaches a maximum when the amplitude of oscillations along the direction of mean drift equals the drift velocity. The damping of waves entering a pack increases with increasing drift velocity, so waves entering a drifting pack will vary in amplitude because of dissipation. The dispersion of surface gravity waves in an ice pack under compression shows that the group velocity of the waves decreases with increasing mean compressive stress, so there can also be dispersive mechanisms causing wave amplitude variations within the ice pack. The observations in the Norwegian Remote Sensing Experiment, namely that the drag in a drifting pack varied with distance from the pack edge, are in general concord with these results.