EuroSITES will integrate and enhance the existing European open-ocean observational capacity to encompass the ocean interior, seafloor and subseafloor. It will produce a more reliable ocean observatory network with common funding streams and data management systems. The network will also enhance the development of more sophisticated sensors to measure more complex properties of the oceans. This will allow a greater understanding of the impact of the changing global Ocean and Earth on mankind and ecosystems at large. This has implications for policy makers, production industries (e.g. fisheries, agriculture) service industries (e.g. insurance) and society at large.