The international GODAE experiment, the first international, 'full scale', operational oceanography project, began in 2003. Its goal is to demonstrate that it is possible to observe, model and predict the state of the global ocean in three dimensions on a routine, real-time basis.GODAE (Global Ocean Data Assimilation Experiment) is a practical demonstration of how real-time assimilation of ocean data on a global scale can provide regular, complete descriptions of ocean temperature, salinity and current fields for operational oceanography as additional information for seasonal forecasting and research models.As a GODAE Partner, Mercator Ocean is one of the patron agencies. It is also a member of the International GODAE Steering Team (IGST). The Mercator system is one of the programme's pilot systems.In 2003 GODAE began its 3-year demonstration phase, during which all of the various observation, analysis and forecasting systems and applications are to be deployed and implemented. With the implementation of its 2nd Mercator prototype (PSY2: for the North Atlantic and Mediterranean at 1/15° and then for the Global Ocean at 2°). In 2003, Mercator Ocean has fulfilled one of the two objectives scheduled for this intensive GODAE phase. The second will involve deployment of the Global Ocean component at 1/4° (3rd Mercator prototype). Mercator Ocean has thus now become one of the leading international contributorsGODAE is contributing to development of its two pilot programmes: ARGO (deployment of profiler floating buoys) and GHRSST (Global High Resolution SST).