A regional data set of water constituent concentrations and inherent optical properties (light absorption and scattering coefficient) for the German Bight and adjacent waters (River Elbe, North Sea, UK waters, and Southern Norwegian Sea) is presented. The data provide high quality results of in situ measurements and laboratory analysis of samples taken at sea, mainly from the mixed layer, during the years 2008 to 2021. Parameters of the water constituents include concentrations of chlorophyll a, particulate organic and dissolved organic carbon (POC, DOC), total suspended matter (TSM), organic suspended matter (OSM) together with water depth, temperature, salinity, and turbidity. Inherent optical properties (IOPs) are given spectrally as light attenuation, scattering and absorption coefficients. This includes coefficients of light attenuation by all non-water matter (cgp) and particulate matter alone (cp), light absorption by all non-water matter (agp), particulate (ap) and dissolved matter (Gelbstoff, ag), non-algal matter (anap) and phytoplankton (aph), and total scattering (bp) and backscattering (bbp) by particulate matter. The combination of concentrations and IOPS is used to determine specific IOPs of German Bight water and in optical modelling of coastal waters to interpret surface reflectance spectra like in satellite remote sensing approaches.