France holds one of the largest underwater territories in the world, with nearly 9.5 million square kilometers of seabed lying at depths greater than 1,000 meters. Despite this vast area, much of it remains unexplored. A recent study from the Observatoire Maîtrise des Fonds Marins—a research body integrated into the strategic program of the French Ministry of Defense and led by the FMES Institute—highlights the challenges France faces in asserting its control over these deep-sea regions. As the seabed becomes an increasingly strategic area of global competition, it hosts critical infrastructure such as undersea cables, holds potential resource deposits, and serves as a testing ground for emerging military and technological advancements. The study outlines three key priorities for France: improving its understanding and protection of underwater areas, ensuring the freedom to act in the face of threats to vital infrastructure, and developing a thoughtful approach to resource exploitation in the deep sea. France has considerable strengths in science, industry, technology, and diplomacy that could support these goals. However, the report also identifies two major challenges. The first is organizational, as the management of the seabed involves many different actors, making it difficult to create and implement a unified strategy. The second challenge is industrial and financial, as funding often falls short of what is needed to turn scientific discoveries and experimental technologies into large-scale, operational capabilities. In a growing environment of global competition, the Observatoire Maîtrise des Fonds Marins emphasizes the need for better coordination among various stakeholders, stronger national capabilities, and reinforced international partnerships. Simply having a vast underwater domain is not enough to ensure control over it. France must also be capable of exploring, monitoring, protecting its infrastructure, and exercising sustainable freedom of action within these deep-sea regions. The study serves as a reminder that effective seabed governance requires not only territorial claims but also the technical and strategic means to maintain influence in this critical, yet largely uncharted, domain.