The perception of ocean areas by policy-makers or by people, living or not on the coast, has significantly varied over centuries. Due to its vastness and complexity, the sea has been studied within distinct academic disciplines. However, the current issues related to the sea, such as climate change, marine pollution or coastal tourism, require an integrated vision of the assets and drawbacks in order to meet the challenges arising from human activities both at sea and onshore. In this study, a group of foresight officers from the French network of public research institutes decided to cross-check and compare several science approaches (biology, sociology, economics, etc) about oceans. Thus, 11 sectors of maritime activity (transportation, fisheries, energy, etc.) were cross-tabulated with 9 basic social functions (providing food, housing, learning, etc.). In this matrix, the main challenges and issues projected for 2030 were sought, in the frame of a baseline scenario. Results were clustered through 4 criteria, leading to 9 major challenges, each of them broken down into two important issues for research. The outcomes were used to create a survey, allowing the ranking of the research priorities. Most of the 9 challenges tally with the research and development objectives of great maritime states, except for governance and monitoring, which remain underscored. As a result, maritime powers still show more interest on securing national resources rather than on promoting international cooperation for secure trade and sustainable exploitation of marine resources. But foresight in this field could help changing the mentalities notably because oceans show clearly now to be a vital common good for mankind.