The world’s oceans now operate under a single, sprawling rulebook. As of October 2024, 169 countries plus the European Union are party to the United Nations Convention on the Law of the Sea — UNCLOS. That number represents nearly every coastal nation on Earth. It also means the rules governing shipping lanes, fishing rights, and seabed mining are, for the most part, settled law. The question is what happens to the waters that fall through the cracks.
Those cracks are vast. International waters — the high seas — cover nearly two-thirds of the ocean’s surface. They are the planet’s biggest ungoverned space, a zone where no single country has jurisdiction and where enforcement is thin to nonexistent. For decades, that meant anyone could take what they wanted. Overfishing, plastic dumping, and deep-sea mining proposals all played out with little legal pushback. UNCLOS provided a framework, but it left the high seas largely undefined.
That changed in 2023. A new High Seas Treaty was agreed upon, set to be added as an instrument under the UNCLOS umbrella. The deal is blunt in its ambition: create marine protected areas in international waters, mandate environmental impact assessments before new projects begin, and give ocean life a fighting chance. No country can do this alone. The treaty is a direct acknowledgment that the old system of voluntary restraint failed. It replaces good intentions with legal obligations.
The stakes are concrete. Fish stocks do not respect national borders. A tuna caught off the coast of one country may have been spawned in international waters, then poached by a vessel flying a flag of convenience. Plastic waste from a river in Southeast Asia can end up in the guts of a seabird in the South Pacific. The High Seas Treaty is the first serious attempt to close that enforcement gap. It creates a mechanism for countries to agree on protected zones and to hold each other accountable.
None of this happened overnight. UNCLOS itself took nine years to negotiate, from 1973 to 1982. It only entered into force in 1994, after Guyana became the 60th nation to ratify. That is a 21-year gap between signing and enforcement. The High Seas Treaty will likely face a similar slog. Ratification by enough countries to trigger its implementation is not guaranteed. And even then, the real work — policing vast stretches of ocean, funding conservation, resolving disputes — will fall to the same nations that have struggled to cooperate on climate change and biodiversity.
The United States remains on the sidelines. It has not ratified UNCLOS, despite playing a central role in drafting it. That absence matters. The U.S. Navy operates globally. American fishing fleets work in international waters. Without ratification, Washington has a seat at the table but no vote on the rules. It can influence negotiations but cannot formally block bad ones. The High Seas Treaty will move forward regardless, but its effectiveness is diminished without the world’s largest economy fully bound by its terms.
What is at risk is not abstract. The ocean absorbs about a quarter of human-caused carbon emissions. It generates half the oxygen we breathe. The High Seas Treaty is a tool to protect the engine of that system. Marine protected areas, if properly enforced, can allow fish populations to recover. Environmental impact assessments can stop the worst offshore mining projects before they start. These are not hypothetical gains. They are measurable, tangible, and time-sensitive.
The treaty is a bet that governments can work together when the alternative is collective loss. It is a fragile bet. The high seas are vast, and enforcement is expensive. But the alternative — no rules at all — has already been tried. The results are visible in dead zones, collapsing fisheries, and plastic islands. The High Seas Treaty is not a cure. It is a legal foundation. Whether countries build on it or ignore it will determine the health of the world’s oceans for generations.
