Underwater landscapes, from shallow coastal zones to deep oceans, are shaped by geologic, biologic, oceanographic and anthropogenic processes. The resulting morphologies are manifold and their description and quantification provide critical insights into associated underlying processes. Many such processes act at multiple spatial and temporal scales, and their understanding is key for a safe and sustainable use of coastal regions and the assessment of offshore geohazards. This interdisciplinary session aims to examine the causes and consequences of processes shaping underwater landscapes, including erosional and depositional dynamics, gravitational driven and current-induced sediment transport, submarine landslides, active deformation, volcanic activity, fluid migration and escape, faulting and folding, and other processes responsible of seafloor geomorphic changes. Contributions to this session can include work from marine or lacustrine environments and all physiographic regions such as coastal oceans and marginal seas, oceanic plateaus, abyssal hills, mid-ocean ridges, accretionary wedges, continental shelves and margins. We welcome integrative studies that combine satellite-derived and hydroacoustic seabed characterizations, visual observations, seismic images of the sub-seafloor as well as sedimentary, geochemical, and geological seabed samples. Such interdisciplinary studies provide an exciting opportunity to integrate the approaches of geomorphology and geophysics, and to extend quantitative geomorphology offshore.