A frontier mentality has been a defining aspect of human history. Often this sentiment is optimistically framed in the language of aspirations and opportunities. But it can also be accompanied by unsavory narratives of over-exploitation, inequity, and conflict (1). If any place on Earth can be considered a final frontier, it is perhaps the ocean’s “areas beyond national jurisdiction” (ABNJ), which are both distant (generally starting some 370 km from coastlines) and vast (covering nearly 40% of the planet’s surface). It is also the subject of ongoing United Nations negotiations for a treaty on the conservation and sustainable use of marine biological diversity found in areas beyond national jurisdiction (typically shortened to BBNJ, https://www.un.org/bbnj/). However, if current trajectories of expansion of human activities in the ocean continue, we are at the crossroad of deciding whether this rapidly receding frontier will bring the economic and social benefits that drive progress towards achieving the Sustainable Development Agenda or further cement global inequities (2). To preserve the global ocean commons, we need to explicitly focus not just on scientific questions worthy of investigation but also on building up the capacity of emerging and future researchers. Image credit: Shutterstock/LeQuangNhut. Humanity has never benefited more from the ocean, but 60% of USD 1.8 trillion revenues of the eight main ocean-based sectors were accrued by just 100 corporations (3). Almost half of these are oil and gas companies headquartered in 13 countries, emphasizing the distance between today’s ocean economy and aspirations of a sustainable and equitable “blue economy” (4). Over the past 50 years, this concentration has been accompanied by accelerating growth in the diversity and scale of claims on the ocean’s food, material, and space, not only in coastal areas, but increasingly in international waters [the Blue Acceleration (5)]. For instance, industrial fishing fleets … [↵][1] 1To whom correspondence may be addressed. Email: joachim.claudet{at}cnrs.fr. [1]: #xref-corresp-1-1