The movement of rubble on coral reefs can lead to persistent unstable rubble beds that hinder reef recovery. To identify where such rubble beds are, we need to know the minimum velocity that will move rubble. We found that loose rubble had a 50 % chance of being moved when near-bed wave orbital velocities reached ~0.3 m s⁻¹; rubble moved more if pieces were small and had no branches. Rubble beds that experience frequent movement would be good candidates for rubble stabilisation interventions.