'It belongs to all of us': How the High Seas Treaty is shaping global waters

"The high seas cover two thirds of the global ocean. That's almost half the planet," Nathalie Rey, Senior Strategy Advisor at the High Seas Alliance, tells Euronews Earth.

But until January this year, there was no legal framework dedicated to protecting these international waters and sharing their resources fairly among nations.

The High Seas Treaty – formally the Agreement on the Conservation and Sustainable Use of Marine Biological Diversity of Areas Beyond National Jurisdiction, or BBNJ – entered into force on 17 January 2026.

It is the first binding international agreement focused specifically on protecting biodiversity in waters beyond any country's jurisdiction, covering an area that makes up two thirds of the global ocean and nearly half the surface of the Earth.

The high seas begin where national waters end – beyond 200 nautical miles, roughly 370 kilometres, from shore. "To put that into perspective, that's about the distance between London and Paris," says Rey.

That vast expanse is also part of what Rey calls the global commons. "It belongs to all of us," she says. "So we all have this responsibility to look after it."

Around 2,000 new species are discovered there each year, and the high seas play a critical role in regulating the climate cycle and the water cycle, as well as supporting global food security.

'A patchwork of ocean governance'

Until now, governance of the high seas has been fragmented. "We have had a patchwork of ocean governance – different bodies responsible for shipping or fisheries," Rey says, "but their main mandate has been around extraction and use and not protecting this area."

Threats have grown as technology has advanced. Overfishing, bottom trawling, plastic and chemical pollution, deep-sea mining, geoengineering and climate change all bear down on waters that, until this year, had no overarching legal protection.

Negotiations to close that gap took more than two decades, involving over 190 countries. "I don't think the negotiations actually broke down," Rey says. "Political change takes time."

A global pandemic also delayed progress by several years. The final text was agreed in 2023, and the treaty reached the 60 ratifications required to enter into force within two years – fast by the standards of international law.

"Some can take a decade to enter into force," Rey notes. "It just shows how much political support is behind this treaty." As of the time of the interview, 89 countries had ratified it.

France played a prominent role in building political momentum, pushing for the treaty to be a key deliverable at the UN Ocean Conference it hosted in 2025. "There was a real political push from France, but also many [other] countries," says Rey.

What the High Seas Treaty changes

The treaty offers a practical tool to deliver on existing commitments, bridging long-standing gaps in ocean governance by promoting cooperation across frameworks such as the Barcelona Convention, regional fisheries bodies and maritime organisations.

It establishes, for the first time, clear legal processes for creating marine protected areas on the high seas – how proposals are developed, agreed and enforced. It also introduces mandatory environmental impact assessments before harmful activities can begin.

But Rey highlights a second, less-discussed dimension: ocean justice. Under the treaty, developing countries will have fairer access to the benefits of the global commons – including marine genetic resources found in deep-sea organisms such as sponges, which can lead to pharmaceutical breakthroughs.

"At the moment, it's only been those countries or companies that have had the resources to be able to exploit that [who] see the benefits," she says. "And this is part of a global common."

The treaty also commits to building the capacity of developing nations to participate in marine scientific research and to implement the agreement themselves.

On enforcement, Rey acknowledges the complications: "It's going to be a challenge to police," she says, "but we are seeing such advances in technology and monitoring – including satellite monitoring – that actually it's not always necessary to be out on the ocean itself to be able to see what's happening." Satellite tools can already track fishing activity in remote waters without a physical presence at sea.

Importance for the Mediterranean

The treaty is particularly important for the Mediterranean, which covers less than one per cent of the global ocean but hosts around 18 per cent of known marine species.

Despite being one of the world’s most important biodiversity hotspots, governance of its deeply interconnected ecosystems is fragmented across different sectors and jurisdictions. This makes it difficult to address cumulative impacts or manage shared resources effectively, WWF explains.

The conservation organisation says the region is therefore one of the clearest real-world applications for how effective the treaty's implementation can become.

Through tools such as marine protected areas, environmental impact assessments and capacity-building mechanisms, the agreement enables countries to move from commitments to concrete action, WWF says, calling on countries that have not yet ratified the treaty to do so.

From paper to action: Shaping how the High Seas Treaty works in practice

The risk of the treaty becoming what Rey calls "paper parks" – protected in name only – is real, she concedes. "That's always a concern." But she points to features designed to prevent that outcome. Unlike many international agreements, this treaty allows countries to vote on marine protection proposals rather than requiring full consensus – meaning a single country cannot block progress indefinitely. "It's not down to one or two countries that can block progress," Rey says.

The High Seas Alliance, a coalition of more than 80 environmental organisations that campaigned for the treaty throughout the negotiation process, was recognised as a winner of the Earthshot Prize in 2025. Rey describes it as recognition of "the power of joint effort between the governments and the scientists and Indigenous people, local communities, youth and civil societies working together."

The immediate next step is the first Conference of the Parties for the UN High Seas Treaty, due to be held in January 2027. It will establish the treaty's governing bodies, rules of procedure and key processes, shaping how it works in practice and determining its level of ambition.

"The amount of political focus and support will be absolutely vital to make sure that it does move from just words on paper to action on the water," says Rey.