Britain has ratified the landmark High Seas Treaty to help protect two thirds of the world’s oceans.

The treaty, also known as the Biodiversity Beyond National Jurisdiction Agreement, could not be ratified independently of Britain by Bermuda, as a subcontinental island jurisdiction.

Noelle Young, a local environmental campaigner who has been advocating for inclusive implementation of the treaty for Bermuda, said it was an important moment for ocean conservation. The UK joins a growing number of countries ratifying the international agreement.

Ms Young told the The Royal Gazette: “I'm so happy I could swim laps around the island.

“I received the news while I was at 9 Beaches snorkelling with my son, and there couldn't have been a more perfect moment — surrounded by the ocean that we have been working so hard to protect.

“I would like to congratulate the United Kingdom and, in particular, His Majesty King Charles III on formally ratifying the High Seas Treaty. This important milestone demonstrates the value of moving the legislation forward through Royal Assent and reflects the UK's commitment to working alongside its subnational island jurisdictions as implementation of the treaty begins.”

The UK Government said the agreement would strengthen protections for marine biodiversity in regions outside national jurisdiction. These areas make up almost two thirds of the world’s oceans.

The treaty establishes a legal mechanism to create marine-protected areas on the high seas with the aim of conserving vulnerable habitats and species.

The UK Government said on its website when the ratification took effect on Friday: “The Foreign Secretary has now signed the document required for the UK to ratify the BBNJ Agreement.

“Today, this will be formally deposited with the United Nations in New York, completing the final step of the process.

“Having played a leading role in shaping the agreement over more than a decade of negotiations, the UK was among the first countries to sign it in 2023.

“Today’s ratification marks the culmination of that commitment and enables the UK to play a full role in implementing the agreement.”

Ms Young hopes that Bermuda and other subnational countries can have their own voice in the future decision-making processes of the treaty.

She said: “Bermuda has a unique perspective to offer as the only nation within the Sargasso Sea.

“Bermudians have centuries of generational knowledge and deep cultural connections to these waters that can help inform the development and management of future marine-protected areas.

“Moving forward, I hope local communities are viewed not simply as stakeholders to consult but as genuine partners in shaping the future of marine protection.

“I hope this marks the beginning of an implementation process that is transparent, inclusive and grounded in both the best available science and local knowledge.

“International agreements of this scale require strong leadership, collaboration and perseverance. This announcement represents the culmination of years of work by governments, scientists, indigenous peoples, NGOs and communities around the world.”

The High Seas Treaty was adopted by UN member states in 2023 after more than a decade of negotiations.

The agreement came into force in January 2026 and the first Conference of Parties is scheduled to take place in January 2027.

The treaty also supports the delivery of the Kunming-Montreal Global Biodiversity Framework, which includes the global commitment to protect 30 per cent of the world’s land and oceans by 2030.