FLOWBEC aims at measuring FLOW, Water Column and Benthic ECology in 4 dimensions to assess the potential effects of Marine Renewable Energy Devices (MREDs) on the environment. It addresses clear knowledge gaps identified by NERC, DEFRA and UKERC in the effects of MREDs on flow conditions, habitats and ecological interactions. It will use a wealth of observation techniques above and under water, ranging from radar to sonar and in situ measurements, to be deployed over 2 years at 3 key sites around the UK. These measurements will feed into models of ecological interactions and habitat preferences, allowing predictions of the multiple effects of large MRED arrays. Being fully cross-disciplinary, this project will engage different academic beneficiaries at each stage. Researchers in the field of instrument design (in the laboratory and at sea) will benefit from our experience in building the different systems and adapting them to long-term deployments on the seabed, in extremely challenging environments. This will be done by carefully planned Knowledge Exchange activities and open-access publication of our results, as well as exchange of personnel. The avenues opened for continuous imaging of complex and dynamic 3-D structures will be useful to researchers in other fields associated with ecological systems and marine structures, but also in medical 4-D imaging.