The principal aim of the Sea and Land Surface Temperature Radiometer (SLSTR) instrument mission aboard Sentinel-3 is to provide a reference Land Surface Temperature and Sea Surface Temperature dataset for climate data records. SLSTR has been developed to retrieve global coverage sea surface skin temperatures with zero bias and an uncertainty of ± 0.3 K for a 5° by 5° latitude–longitude area, having a temporal stability of 0.1 K/decade. The instrument has been designed to fulfill these mission aims.