As 2025 draws to a close, and while the physical state of the world’s oceans remains under intense pressure from climate change, the past 12 months have seen some fundamental shifts in how nations could manage the high seas and coastal waters in the future.
The most significant legal milestone occurred as the Global Ocean Treaty officially secured the ratifications necessary to become international law. As reported by Greenpeace, the treaty is set to enter into force in early 2026, providing the first-ever legal framework for creating marine sanctuaries in international waters. This is seen as a critical step toward the “30×30” goal—the global ambition to protect 30% of the world’s oceans by 2030.
French Polynesia made history by designating its entire Exclusive Economic Zone as a marine protected area. At nearly 5 million square kilometres, it has become the largest protected area in the world. According to the International Union for Conservation of Nature (IUCN), President Moetai Brotherson announced the move at the UN Ocean Conference in June, stating that it asserts “ecological sovereignty” while creating sanctuaries for future generations. The designation includes over 1 million square kilometres of “highly or fully protected” zones where industrial fishing and deep-sea mining are strictly prohibited.
However, these conservation gains have been tempered by stark scientific warnings. In September, The Guardian reported that the world’s oceans have failed a key planetary health check for the first time. Scientists from the Potsdam Institute for Climate Impact Research confirmed that ocean acidity has crossed a “critical threshold,” making it the seventh of nine planetary boundaries to be transgressed. This shift poses a severe threat to marine organisms that build shells and skeletons, such as corals and molluscs.
The shipping industry also faced a year of escalating regulation. As reported by Ship & Bunker, 2025 saw the full implementation of the “FuelEU Maritime” rules and a significant expansion of the EU Emissions Trading System (ETS), requiring vessels to pay for a larger share of their carbon emissions.
The engine of international diplomacy this year was the Third UN Ocean Conference (UNOC3), held in Nice, France, in June. The summit concluded with the adoption of the “Nice Ocean Action Plan,” which generated over 800 voluntary commitments totaling billions in new funding. As reported by the UN, France and a coalition of global partners pledged €8.7bn to accelerate marine restoration and the decarbonization of the maritime sector.
The World Trade Organisation (WTO) Agreement on Fisheries Subsidies officially entered into force on 15 September 2025. After two decades of negotiations, the deal reached the required two-thirds ratification milestone, making it the first multilateral binding agreement at the WTO to focus on environmental sustainability. As reported by the World Resources Institute, the agreement prohibits government subsidies for illegal, unreported, and unregulated (IUU) fishing and for the exploitation of overfished stocks. WTO Director-General Ngozi Okonjo-Iweala stated that this “landmark achievement” marks a decisive step toward curbing the government incentives that drive the overexploitation of the ocean.
As the year concludes, the European Union’s “Ocean Pact” has committed over €1bn in new funding for marine restoration, highlighting a global trend toward “blue finance.” While the 2025 review shows a planet still grappling with the climate threshold, the unprecedented scale of new marine protected areas suggests a growing political will to defend the high seas.