This is an inter-disciplinary session that seeks to bring together scientists working on all aspects of interfaces in the aquatic environment. These boundary regions are characterised by steep gradients in physical and biochemical properties and are locations where important interactions take place between water, sediments and biota and critical biophysical processes occur creating hot spots of ecosystem functioning. However, despite their hydraulic, hydrological, geochemical and ecological significance, interfaces are some of the least understood aspects of aquatic systems, in part because of the technical challenges of working on the inter-linked biophysical processes in these zones, which often occur at the micro scale of individual sediment grains or organisms. There are currently many gaps in our understanding of interfaces, which need to be addressed to underpin more ecologically-appropriate management. These include the need to develop a fully integrated understanding of coupled hydrodynamic, morphodynamic, geochemical, biological and ecological processes in hyporheic zones; the need to build multi-scale models of the flow-sediment interface that can advance understanding of sediment dynamics and the flux of sediment-bound contaminants; and the need to establish the role of water-sediment interfaces in the adaptation of individual organisms and ecosystem functioning. We believe these challenges will be addressed and new insights gained by working at the discipline boundaries. We, therefore, invite papers on the processes occurring at aquatic interfaces, papers that report on new approaches to studying aquatic interfaces (experimental, field and modelling) and papers that demonstrate how advances in the scientific understanding of aquatic interfaces can be translated into improved management of aquatic environments.