We present an overview of a large collaborative field campaign, in which we collected a long-term (months) high-resolution (4 Hz measurement frequency) hydrodynamic data set for several locations at the mudflat–salt marsh ecosystem and linked this to data on sediment transport and to a biological description of the organisms on the mudflat and the marsh. In this paper, part of this database has been used to identify general relationships that can be used for making hydrodynamic characterisations of mudflat–salt marsh ecosystems. We observed a clear linear relation between tidal amplitude and the maximum current velocity, both at the mudflat as well as within the marsh vegetation. Velocities in the vegetation were however a magnitude lower than those on the mudflat. This relationship offers promising possibilities for making hydrodynamic habitat characterisations and for validating hydrodynamic models.