This session addresses a deficit in our understanding of high-energy coastal environments. Until recently, it was generally accepted in the scientific community that only tsunami have enough power to transport very large boulders (VLB). However, the winter of 2013-2014 in Europe clearly showed that storm waves can also move VLB. As coastal populations grow, sea level rises, and climate models predict increasing storminess with greater coastal inundation levels, there is a need for a better understanding of the geomorphologic expression of strong storm events. The purpose of this session is twofold: (1) to provide a more definite answer to the question "storm or tsunami ?" and (2) to improve our modelling and prediction of the effect of storm waves on coasts by bringing together experts in different fields such as geosciences, ocean engineering, water waves, applied mathematics, statistics.