Here’s what you need to know about the first international agreement focused on protecting marine biodiversity in international waters.
In March 2023, the UN building in New York burst into wild applause. After nearly 20 years of negotiations, the High Seas Treaty had finally been adopted.
The treaty, also known as the Biodiversity Beyond National Jurisdiction, or BBNJ, agreement, aims to protect and share the benefits of biodiversity, marine resources and unique species in the high seas – that two-thirds of the ocean that is not controlled by any country. It will come into force on 17 January next year, 120 days after being ratified by 60 countries. Ratifying involves formally agreeing to be bound by the treaty.
Campaigners had hoped the UN Ocean Conference in Nice this June would see that number reached, but it was not to be. A surge of nations did ratify at the meeting, taking the number to 50. The crucial 60 was reached on 19 September.
“This historic moment is the culmination of years of dedication and global diplomacy by governments and stakeholders,” said Rebecca Hubbard, director of the High Seas Alliance. But she added: “Achieving 60 ratifications is not the finish line – it’s just the starting block.”
Dialogue Earth examines what happens next, and what remains to be determined.
In this explainer:
What are the high seas?
Why is the High Seas Treaty needed?
What happens once 60 countries have ratified?
How will high seas marine protected areas be created?
Who will protect high seas MPAs?
How will resources be shared?
How will this impact deep-sea mining?
What about countries that do not sign up?
How long will it take to make an impact?
What are the high seas?
The high seas are the ocean beyond the rule of nations. Though sometimes referred to as “lawless”, there are around 20 international bodies that govern different parts of them, each with their own mandate.
But these mandates still leave much of the ocean unregulated and often unprotected.
The high seas are among the largest reservoirs of biodiversity on the planet – from deep-sea corals to giant tube worms. They also play a vital role in the climate system, absorbing and storing carbon dioxide from the atmosphere. Yet they face growing pressures: climate change, industrial fishing, pollution, increased vessel traffic and (potentially) deep-sea mining.
Why is the High Seas Treaty needed?
To better protect the high seas, the treaty introduces a more coordinated approach and conservation tools that go beyond the long-standing UN Convention on the Law of the Sea (Unclos).
“I think the world realised we needed to do something. When Unclos was put together, most of the activities were very close to shore. But as we deplete coastal waters, where do people go? Suddenly we realised the high seas are also in trouble,” says ocean economist Rashid Sumaila of the University of British Columbia in Canada.
Robert Blasiak, associate professor at the Stockholm Resilience Center, says that without the treaty, there is no mechanism for establishing protected areas on the high seas. There are also no systems for sharing benefits from animals, plants and microbes found there, no rules for carrying out environmental impact assessments, and major gaps in technology transfer and capacity building.
What happens once 60 countries have ratified?
The treaty enters into force 120 days after enough countries have ratified. A first Conference of Parties (COP) meeting also has to happen within a year, and there is currently a push from some groups to make COPs annual in the early years of the treaty.
A secretariat for the treaty will also have to be set up and a location chosen to host it. Chile has suggested it is the best country for this, as has Belgium.
Much of the treaty’s structure is being decided during UN Preparatory Commission meetings, which began in April. While no decisions can actually be made until the first COP, these Prepcom meetings are laying the groundwork.
“The text of the treaty has left so many details up for discussion, particularly in setting up the institutions and processes to bring the high seas treaty into life,” says Rizza Sacra-Dejucos, Asia regional coordinator for the High Seas Alliance.
How will high seas marine protected areas be created?
A scientific and technical body for the treaty will be launched, to which countries can submit proposals for marine protected areas (MPAs): specific sections of the ocean that ban certain types of activity such as fishing. The body will review the proposals along with feedback from governments, scientists, NGOs and businesses, and give advice to the COP. National representatives at the COP will then vote. Even if they do not all agree, a new protected area can still be created if three-quarters of countries vote for it.
Some NGOs have already begun work to push for high seas protected areas, for example around the Nazca Ridges in the South Pacific. It is still unclear if there will be one central managing body or separate teams for each MPA, but countries located near a proposed MPA are likely to be more involved in managing and monitoring it.
Who will protect high seas MPAs?
The treaty will not impose sanctions, but assumes nations will work to support protected areas. “When a country signs the treaty, it’s committing to basically not do anything that undermines the objectives of the treaty. This means that countries that sign signal they will follow MPAs,” says Rebecca Hubbard, director of the High Seas Alliance, a network of NGOs interested in high seas issues.
Countries that have signed the treaty but not ratified it are not legally bound by it, meaning they could simply ignore MPAs created by it. “But then they would be acting against the purpose of signing the treaty,” Hubbard notes.
Countries also have a right to opt out. For example, when an MPA is being discussed, each party that has ratified the treaty can object on the basis of one of three available grounds: that the decision to create a protected area is inconsistent with the treaty; that it “unjustifiably discriminates” against the country objecting; and that the objecting country cannot comply with the decision despite making “all reasonable efforts”. If they do this, and an MPA is still created, that decision will not be binding on them.
How will resources be shared?
The treaty states that nations should share “marine genetic resources” (MGRs) found in the high seas. This includes all animals, plants and other organisms found in the ocean, which scientists might want to research and companies might wish to exploit. Fishing is largely excluded, however.
The idea is that anyone collecting these MGRs must make their discoveries known via a “clearing-house mechanism” – an open-access platform for sharing biodiversity findings with other countries, details of which will be decided by the first COP. If these resources – maybe a plant or bacterium – lead to profit, wealthier countries are expected to pay into a shared fund that helps support research and training in less wealthy nations. The treaty also aims to share scientific information and research results, as well as equipment and technology. According to Blasiak, who works closely with MGRs, this has “consistently been neglected in past agreements”.
The specific financial mechanism for distributing the resulting money is still to be decided. One option is that all profits would go into a common fund administered by the treaty body, to support research capacity and training in developing nations and to further support marine conservation.
To fund the operation of the treaty, all parties will be required to pay, with developed nations likely to fork out a larger share. There will also be a voluntary fund paid for by wealthier nations that uses its money to build capacity including scientific expertise and technology in developing countries so they can participate in the treaty fully.
The first COP meeting should decide exactly how the treaty’s funding mechanism will work.
How will this impact deep-sea mining?
One of the big unanswered questions is how the High Seas Treaty will end up working with existing bodies, such as the International Seabed Authority (ISA), which regulates deep-sea mining, and the regional fisheries management organisations (RFMOs), which oversee some fishing activities in parts of the high seas.
“The agreement was negotiated with the recognition that there are already some existing bodies with mandates in the high seas. However, they are fragmented, and one of the objectives is to enhance coordination among them. The challenge will be how this will be put in practice,” says Nathalie Rey, regional coordinator for Europe at the High Seas Alliance.
One concern is how other organisations, including the ISA, will work with the treaty’s environmental impact assessment (EIA) rules. EIAs are formal studies that look at how a proposed activity, such as deep-sea mining, might affect the ocean.
The ISA is still developing its own regulations and standards for deep-sea mining. This will require some care given the number of countries that are parties to both the BBNJ and Unclos, of which the ISA is a part. “Parties [to both BBNJ and Unclos] will need to cooperate and coordinate within the ISA to ensure that EIAs are carried out consistently with the High Seas [Treaty],” Rey explains.
Most countries involved in deep-sea mining are ISA members, with the notable exception of the United States. So even if they have not signed the BBNJ treaty, they still have to follow ISA rules. Some fear that any differences between ISA and BBNJ rules could create gaps in how well the treaty protects the ocean.
What about countries that do not sign up?
Protecting two-thirds of the ocean requires a great deal of political will. Effectiveness of the treaty may also be compromised if major nations do not sign up.
By 19 September, 143 countries had signed, indicating that they endorse it but are a step short of ratifying, which involves being bound by it. Signatories include key maritime nations like China, the UK and India, as well as several EU and Pacific states.
“A country is only bound by the rules if it has ratified the agreement. That is why universal ratification is so important,” says Lisa Speer, director of the international oceans programme at NGO the Natural Resources Defense Council.
Palau was the first country to ratify in January 2024, followed by Chile in February. They have been joined by countries from across the ocean including Jamaica, Indonesia, Spain and Mauritania. Even landlocked countries have joined in, with Malawi and Hungary ratifying. The US has signed but is unlikely to ratify. Russia is yet to sign.
“If Russia is not going to ratify the BBNJ agreement, you have a key player that will not be bound by the treaty. That will limit its potential effectiveness”, says Vito De Lucia, director of the Norwegian Centre for the Law of the Sea.
Another difficulty will be areas such as the South China Sea where there are territorial disputes. “This treaty will function more directly in areas where there is no conflict,” De Lucia admits.
How long will it take to make an impact?
There is a lot to be done before the BBNJ delivers real change on the water.
“Having the first high seas MPAs established through the BBNJ Agreement before 2030 would be a remarkable success,” says Blasiak.
And what happens once it is finally in place?
“I once joked that the day we close the high seas to fishing, I’ll retire. Maybe that goes for this too!” laughs Sumaila.
This explainer, first published in June 2025, was updated in September 2025 to reflect the treaty being ratified by 60 nations and other developments.
