Reliable satellite-based water quality products can provide valuable information that improves and supports operational monitoring in German coastal waters. However, current Copernicus Marine Service products show varying results when global and regional datasets overlap, particularly in the western Baltic Sea. These inconsistencies, combined with systematic differences between satellite- and in-situ-derived chlorophyll, turbidity and light attenuation parameters, limit their suitability for mandatory assessments under the MSFD. The pilot study addresses this challenge through a structured assessment of Copernicus water quality products, with a particular focus on the shallow coastal waters of the western Baltic Sea. The project includes: a systematic inventory and analysis of all relevant Copernicus water quality products; an in-situ optical measurement campaign in 2026 with ship-based sampling, shallow water moorings and hyperspectral radiometry in the western Baltic Sea; and a comprehensive evaluation of the products based on robust matching methods. The resulting datasets will be used to evaluate satellite reflectance and derived products and to quantify accuracy, spatio-temporal consistency and systematic deviations. The results include prototype workflows for the long-term validation of Copernicus products in shallow coastal areas, recommendations for optimised optical in-situ measurements, and suggestions for improving satellite-based monitoring of German waters.