After a time when observations of the sea have been made for specific purposes, e.g. for specific national purposes or to demonstrate a technological capability, the European Commission has now moved to a new paradigm where data are collected once and used them for as many purposes as possible. This means relying preferably on users rather than on producers to assess existing data sets and data sources and promote recommendations for a better satisfaction of their needs. The EMODNET Atlantic checkpoint (http://www.emodnet-atlantic.eu/) was designed to evaluate the fitness-for-use of current observations and data assembly programs towards 11 marine applications and prioritizing the needs to optimize monitoring systems at the scale of the North Atlantic Ocean.