Blue-Cloud is a European H2020 project aiming to federate and pilot innovative services for Marine Research & the Blue Economy. It will develop a marine thematic cloud for EOSC to explore and demonstrate the potential of cloud based open science for better understanding and managing the many aspects of sea and ocean sustainability. At the opening of the All Atlantic Ocean Research Forum (6-7 February 2020), Mariya Gabriel, the European Commissioner for innovation, research, education and youth, highlighted Blue-Cloud a key instrument for the sustainable ocean strategy. Blue-Cloud is the flagship project of the DG RTD Unit of the European Commission that will link the horizontal e-infrastructures supported by DG CNECT (e.g. EUDAT & D4Science) and DG GROW (e.g. Copernicus DIAS), long-term marine data initiative supported by DG MARE (e.g. EMODnet), research infrastructures supported by DG RTD and other recently funded thematic clouds (e.g. FNS-Cloud and BE OPEN). It federates leading European blue data management infrastructures (SeaDataNet, EurOBIS, Euro-Argo, ENA, Euro BioImaging, CMEMS and ICOS Marine), and horizontal e-infrastructures to capitalise on what already exists and to deliver the “Blue-Cloud” framework. The project holds great potential to deliver societal solutions via the implementation of five innovative demonstrators (www.blue-cloud.org/demonstrators), covering specific domains such as biodiversity and genomics, environment, fisheries and aquaculture. It is aware of the high importance of EOSC and data as a key resource for innovation and is working towards the establishment of a thematic marine EOSC serving the Blue Economy. Through a smart federation of data resources, computing facilities, and analytical tools Blue-Cloud aims to provide researchers with access to: 1) Blue multi-disciplinary data from observations, in-situ and remote sensing, data products and outputs of numerical models. 2) A blue Virtual Research Environment (VRE) with various services to support its users in undertaking world class science. What does Blue-Cloud bring to EOSC? A pilot thematic-EOSC as a role model for the development of other thematic clouds, with FAIR access to multidisciplinary data, analytical tools and computing and storage facilities that support multiple scientific research challenges. Services through pilot Demonstrators for oceans, seas and fresh water bodies for ecosystems research, conservation, forecasting and innovation in the Blue Economy. A mechanism to easily access and discover blue data, with APIs to access blue services that will complement EOSC base services providing blue thematic functionalities. Examples on how a framework like Blue-Cloud can address one or several of the policy challenges defined in many programmes, namely Bioeconomy Strategy, the Circular Economy Strategy, the Blue Growth Strategy, the Common Fisheries Policy, the Maritime Spatial Planning Directive and the International Ocean Governance Communication. A Global Blue-Economy community close to the EOSC vision, including the marine and maritime industry. The opportunity of bringing EOSC in the Blue Economy long-term vision via the policy oriented Blue Cloud Roadmap to 2030 which seeks a series of EU Calls for further development and uptake of the Blue Cloud by multiple VRE applications and connecting additional marine data infrastructures.