The PEACETIME-OC project, funded by the French space agency (CNES), seeks to explore three major topics: (1) To improve our knowledge of bio-optical relationships in the Mediterranean and our understanding of the factors underlying the bio-optical anomalies observed in this region; (2) To investigate the potential of hyperspectral optical measurements for deriving information on phytoplankton community composition in support of future hyperspectral satellite ocean color missions; (3) To explore the possibility of assessing biological production using the diel cycle of optical properties, in view of applications to observations from autonomous in-situ (BGC-Argo profiling floats) and satellite (geostationary ocean color missions) platforms. PEACETIME-OC relies on the unique opportunity offered by the international PEACETIME project, cruise (April-June 2017 in the Med Sea) and collaborations.