The coastal circulation around Vietnam is strongly affected by modulations of wind forcing and riverine input primarily associated with the seasonal change of monsoonal atmospheric forcing. The continental coastal and shelf topography constrain the response of the ensuing circulation, both near the coast in the interior of the Vietnamese East Sea. The biogeochemistry of coastal and offshore waters, as observed in the ocean color, is tightly coupled to the physicalforcing at all scales. Here the authors present concepts for an observational study focused on characterizing the tight coupling between physics and biogeochemistry at two opposite phases of the monsoon. A combination of ship-based and autonomous surveys of physical and optical properties could sample processes associated with stratification, sediment res uspens ion, biological patchiness and adaptation, all of which can be related to properties that can be observed using satellite remote sensing.