||The European Commission's effort to define the scope and components of the maritime economy was initially motivated by the "Integrated Maritime Policy" (2007). This policy package, principally based on coastal environment protection, maritime safety and security, and the European marine observation and data network, also included the development of an EU-wide economic and social database on maritime activities. The IMP database (2009) used experience from EU member states in terms of maritime database development, and conversely was an opportunity to update national contributions.Later, two other packages contributed to broadening EC's approach. 1) The "Marine Strategy Framework Directive" (2008) was a legislation on marine environment protection. Among other things, it required from member states an economic assessment of marine water uses. 2) The "Blue Growth Strategy" (2012) was launched to analyse and stimulate the potential for growth and job creation in maritime sectors, in line with EU's strategy for 2020. The preparation phase included studies assessing the economic significance of blue sectors. These studies were an opportunity to consider the growth potential of maritime sectors and raise the question of how to describe this in the framework of a database.On the basis of national experiences and of the main steps of EC's policy, the present article will address in turn:- The development of maritime databases in member states and at the EC, and their definition of the maritime economy;- Methodological issues concerning the sectoral and geographical approach to an EU maritime database, including the problem of partially maritime sectors, data quality issues, and options for coping with limited information;- The analysis of blue sectors with high growth potential, the methodology used for such analysis based on present and expected growth rates and job creation, and the issues limiting the applicability of this methodology.