The sea-surface microlayer (SML) as a thin boundary layer separates the hydrosphere and atmosphere. Often, concentrations of specific compounds (phytoplankton, CDOM, particles) are higher in the SML, either by physical concentration from the underlying water, production in the SML, or by atmospheric deposition. Light scattering and absorption properties of water and its constituents as well as fluorescence can be used for real-time characterization of organic matter compounds and to study their short-time dynamics as relevant biological and chemical drivers in the SML. The objective here is to assess exchange, conversion, and transformation of the organic matter in and through the SML with unprecedented temporal and spatial resolution. The focus will be on the dynamics in the dissolved and particulate organic matter fraction (CDOM and POM) and in the living microalgae (phytoneuston). Expected results is a conceptual model of the environmental interconnection of optically active matter (OAM) with the bulk organic compounds that includes the relationships between irradiance, temperature and the OAM, as well as the influence of microalgal blooms and atmospheric deposition on the organic matter in the SML.