New high-resolution multibeam echosounder data have been collected in the Irish Sea in the last decade. Sediment waves oriented transverse to tidal flow dominate many parts of the Irish Sea and exhibit an almost continuous spectrum of heights and spacings. Sediment wave growth remains poorly quantified and from the Irish Sea swath bathymetry data, many bedform dimensions have been measured and examined statistically. A strong positive power correlation between sediment wave height and spacing was observed: Delta s = 0.0692 lambda(0.8020) (N=935: r=0.853) while height and spacing only weakly vary with water depth. To assess the main factors influencing sediment wave height and spacing, deviations from the typical hydrodynamically analogue sediment wave geometry in equilibrium are qualitatively and semi-quantitatively investigated in the Irish Sea in conjunction with seabed characteristics. Coarser sediment generally forms larger sediment waves while suppressed sediment growth is found likely due to the limitations in mobile sediment supply and inefficiency of very coarse bedload transport. (c) 2009 Elsevier B.V. All rights reserved.