Over the past few years, Joep van der Zanden has created perfectly identical waves – 40,000 times – in a large ‘wave flume’ (channel). Using advanced measurements, he investigated the effect of these waves on the sand at the bottom of the flume. The results of his work included a detailed description of the effect of breaking waves on the movement of water and on the shifting sands of the seabed. The knowledge obtained in this way is essential if we are to improve existing models and, ultimately, make beach nourishment operations more efficient.