A 40-year data set of ocean reflectance is derived from an atmospherically corrected climate quality record of top-of-atmosphere signals taken from the satellite-based AVHRR sensor. The data set provides a unique view of visible changes in the global ocean over timescales where climatic effects are demonstrable and spans coverage gaps left by more traditional satellite ocean colour sensors. It is particularly relevant to monitoring bright plankton blooms, such as coccolithophores.