The PROSOPE (PROductivity of Oceanic PElagic Systems) cruise took place from the 4th of September (Agadir, Morocco) to the 4th of October (Toulon, France) 1999 aboard the RV Thalassa. There were four main scientific objectives: - To carry out classical process studies, typical of JGOFS. - To focus on small scale biogeochemical processes, in particular at a daily scale. - To study the influence of nitrogen, phosphorus and iron on oceanic fertility. - To conduct a calibration/validation operation for the SeaWIFS color sensor.