Accounting for nearly half of the planet’s surface (or about two-thirds of its ocean), the high seas are a critical component of Earth’s oceanic ecosystem. This ecologically vital “final frontier” serves as feeding, breeding, and nursery grounds for marine life, a migration corridor for migratory species, and a massive carbon sink that helps stabilize the global climate system. These ecosystem services, alongside the abiotic resources found in the high seas, have an estimated total economic value of $423 billion when considering both market prices in the carbon market and incurred social costs from increased carbon emissions. Despite threats to the high seas’ valuable services and resources from destructive fishing practices, shipping, and plastic pollution, the high seas have remained one of the least-regulated parts of the ocean, relying on a fragmented governance structure composed of regional fisheries agreements, shipping conventions, and scattered marine protected areas (MPAs) that account for less than 1 percent of the high seas.
For nearly three decades—from when the United Nations Convention on the Law of the Sea (UNCLOS) entered into force, through years of informal consultations and six sessions of formal negotiations that began in 2017—areas beyond national jurisdiction (ABNJ) lacked a cohesive governance structure. That long effort finally bore fruit in June 2023, when the Agreement under UNCLOS on the Conservation and Sustainable Use of Marine Biological Diversity of Areas beyond National Jurisdiction (the BBNJ Agreement, or the High Seas Treaty) was adopted with 146 signatories and the objective to “ensure the conservation and sustainable use of marine biological diversity,” in the high seas. The BBNJ Agreement became the third implementing agreement to UNCLOS.
It took another two years, until September 2025, to reach the 60-country ratification threshold necessary for the Agreement to become effective. On January 17, 2026, BBNJ finally came into force and, after two months, an additional 26 countries have completed their respective domestic legal processes and deposited instruments of ratification—including Brazil, China, France, Indonesia, Japan, Mexico, Norway, Spain, and Turkey—for a total of 86 parties to BBNJ as of March 17, 2026.
A New Legal Framework for the High Seas: The BBNJ Agreement
Ratifying countries are legally bound to support the conservation and sustainable management of ABNJ through four broad strategies outlined in the Agreement:
- The fair and equitable distribution of benefits from marine genetic resources (MGR).
- The utilization of area-based management tools such as MPAs to balance conservation with sustainable use.
- New, strengthened requirements for environmental impact assessments (EIAs) to improve decision-making.
- Support for capacity building and the transfer of marine technology.
Nevertheless, key institutions, like the Secretariat, the Scientific and Technical Body, and the Clearing House Mechanism, have not yet been fully developed. Within a year, the States party to the Agreement will meet at the first BBNJ Conference of Parties (COP) to operationalize these strategies and key institutions in a multilateral fashion. The BBNJ Preparatory Commission has held two meetings at the United Nations in New York in preparation.
While these meetings indicate progress towards operationalizing the core tenets of the Agreement, additional items remain outstanding that necessitate clarification. For one, the Agreement requires that states follow BBNJ guidelines during activities “within their jurisdiction or control” in ABNJ. Yet, it does not clearly define the concept of jurisdiction nor control beyond its definition in Part XII of UNCLOS, leaving open the question of which State has jurisdiction or control over activities conducted in ABNJ by multinational companies. While this might be easily answerable for activities like mining or fishing where the flag state of a vessel will readily assert jurisdiction in ABNJ, other activities—such as the repair of a subsea cable—are carried out by remotely operated, unmanned underwater vehicles for multinational companies or consortiums.
Additionally, should any MPAs be established, how will they be monitored? And who will be responsible for the enforcement of limits on fishing or other activities within MPAs? So far, satellite technology, coordinated patrols between multiple nations, and using other UN agencies have been raised as viable options for monitoring and enforcement. Given that the BBNJ Agreement does not “override the rules for any industries that already have regulatory bodies overseeing them,” and is “designed to work within the parameters of existing legal instruments, frameworks and bodies,” coordination with Regional Fisheries Management Organizations (RFMOs), the International Maritime Organization, and the International Seabed Authority (ISA) will be critical for setting, monitoring, and enforcing limits and regulations on activities such as fishing, shipping, and deep-sea mining.
These unresolved questions are further complicated by ongoing debates over resource extraction in ABNJ and equity concerns. Starting with equity, as of yet, France is the only G7 country to have ratified the treaty, raising concerns that the financial and technical burden of implementation will fall disproportionately on smaller developing states. These concerns reflect long-standing equity tensions that shaped the negotiations themselves as developing states pushed for MGR to be governed as common heritage, ensuring broad benefit sharing, while others favored preserving freedom of marine scientific research. As it stands, the final Agreement reflects a compromise: monetary benefit-sharing from MGR commercialization will be decided at a future COP, while non-monetary benefits are to be shared now. In practice, advancing equity will require genuine partnership among states party to the Agreement. Furthermore, although the ISA has not yet finalized regulations for deep-sea mining in ABNJ, the United States is currently reviewing an application from The Metals Company to explore and exploit the seabed in the Clarion Clipperton Zone through an expedited, combined process established by the National Ocean and Atmospheric Administration (NOAA) under the Deep Seabed Hard Mineral Resources Act, bypassing the ISA’s rulemaking process. Should the United States lease areas for exploration or exploitation in MPAs in ABNJ, it may lead to complex international challenges.
Implementing the Agreement and What Comes Next
A third and final preparatory meeting will begin March 23, 2026 to finalize key recommendations for adoption at the COP. Whatever recommendations are eventually adopted, it is expected that ratifying countries will institute new implementing laws that introduce new EIA regulations, licensing and notification requirements for research and work relating to marine genetic resources, and adherence to MPA measures. These domestic laws transposing the Agreement are critical given that most maritime activities nowadays are carried out by companies and other non-state actors that are bound by domestic law, not international law.
It is, however, unlikely that any MPAs will be established during this first COP, since the Scientific and Technical Body that would review proposals is yet to be established. With respect to the process, the Agreement itself provides a procedural framework for how MPAs will ultimately be created. Under Articles 19-21, any Party or group of Parties may submit an MPA proposal to the COP. Parties shall “collaborate and consult, as appropriate, with relevant stakeholders,” and proposals submitted must include a geographic description of the candidate area, an assessment of its biodiversity significance against the indicative criteria listed in Annex I, an inventory of existing human activities and their potential impacts as well as a description of the state of marine environment and biological diversity in the area. Before the COP acts, the Scientific and Technical Body would review the proposal and transmit a publicly available recommendation. Should the COP decide to establish an MPA, it would adopt a binding Management Plan that specifies the measures Parties must implement.
Countries can begin preparing proposals immediately and among the early candidates are the Hawaiian-Emperor Seamounts in the North Pacific, the Sargasso Sea in the Atlantic, and the Salas y Gomez and Nazca Ridges off South America. Julian Cordano, a Chilean official, has gone as far as noting that he is already working with conservationists to design an MPA to protect the nutrient-rich waters around the seamounts.
If successful, the BBNJ Agreement has the potential to reshape ocean conservation and sustainable use, at great environmental and societal benefit. For one, the Agreement may serve as a major breakthrough for global cooperation to meet 30 by 30 ocean protection targets under the Global Biodiversity Framework through the establishment of MPAs in ABNJ. Furthermore, a “nature-positive future” facilitated by the pursuit of BBNJ’s objectives could unlock up to $10 trillion in economic value. Beyond macroeconomic gains, effective implementation could strengthen food security for coastal communities that rely on migratory fish stocks, enhance climate resilience by preserving the ocean’s carbon sequestration capacity, and provide greater legal certainty for industry by clarifying environmental standards and expectations in ABNJ.
Success, however, hinges on effective implementation and—ideally—widespread ratification. Ongoing partnerships are seeking to secure and support ratification efforts, and organizations like the Environmental Law Institute will continue to support implementation through policy analysis, legal research and expertise, and technical assistance. This includes our leading work in tracking previous efforts to establish MPAs in the high seas, identifying best practices for EIA programs and area-based management tools, and convening dialogues to navigate emerging legal issues in the high seas related to deep-sea mining.
As the first COP approaches, the BBNJ Agreement stands as a hard-won achievement for conservation – one that reflects decades of multilateral governance efforts and a shared recognition of the importance of the high seas. Whether this achievement is realized in practice will depend on the sustained engagement of governments, experts, and non-state actors in the years ahead. The architecture for a transformative framework for ocean stewardship is in place; the work of filling it is just beginning.
- Oceans and Coasts