Global analysis ready multispectral satellite data from Sentinel-3 satellites. The Sentinel-3's Ocean and Land Colour Instrument (OLCI) sensor provides data with low spatial resolution (~300m pixels) but high spectral resolution, but more spectral bands, improved signal-to-noise ratio, compared to its predecessor MERIS. This sensor has bands selected specifically to accurately estimate qualities for aquatic remote sensing, including chlorophyll-a, sediment load, etc: https://sentinels.copernicus.eu/web/sentinel/user-guides/sentinel-3-olci/resolutions/radiometric Data can be further processed (atmospheric correction, etc) using SNAP https://step.esa.int/main/toolboxes/sentinel-3-toolbox/ Accessed either through API or online web interface.