Marine data products from the Ocean and Land Color Instrument (OLCI-A) operated onboard the Copernicus Sentinel 3A satellite, were assessed using in situ reference measurements representative of various European Seas. Results from the evaluation of spectral inherent optical properties indicated substantial accuracy for the satellite-derived absorption coefficient of pigmented particles , the diffuse attenuation coefficient of downward irradiance , and the backscattering coefficient of marine particles . Conversely, large underestimates were shown for the spectral absorption coefficient of non-water constituents and the cumulative absorption coefficient of colored dissolved organic matter and of non-pigmented particles .