Measurements made using sonar altimeters mounted on an amphibious surveying vehicle are analyzed for root‐mean‐square (RMS) bedform roughness. Observations for 22 days over a 500 m × 700 m area are used to quantify the cross‐shore distribution of roughness and its variability. Large bedforms (with amplitudes 5–50 cm) occur frequently in shallow water (<2 m water depth). However, the patchiness of these bedforms is also largest in shallow water. This is likely owing to the spatial and temporal variability of the waves and currents, of the sediment grain size distributions, and of the large‐scale nearshore morphology. Large bedforms were observed to exist only for mobility numbers <150, above this threshold the RMS roughness was <2 cm and the bed was interpreted to have transitioned to sheet flow conditions. However, the state of the bed (e.g., large ripples, small ripples, flat bed) was not predictable for mobility numbers between about 30 and 150. Existing models for orbital ripples do not predict the observed large bedforms and have little predictive skill for these data.