An exclusive economic zone is a belt of ocean reaching up to 200 nautical miles from a country’s coast, within which that country holds sovereign rights over the natural resources in the water, on the seabed, and beneath it. The framework comes from the 1982 United Nations Convention on the Law of the Sea (UNCLOS), which 172 nations have ratified as of early 2026. The zone gives the coastal state economic control while preserving the rest of the world’s freedom to navigate, fly over, and lay cables through the same waters.
How Far It Reaches and How It’s Measured
The zone begins just past the 12-nautical-mile territorial sea and extends to a maximum of 200 nautical miles from the “baseline,” which is normally the low-water line along the coast as shown on officially recognized charts.1United Nations. United Nations Convention on the Law of the Sea – Part V – Exclusive Economic Zone Fixing the measurement at the low-water mark prevents countries from stretching their reach by starting from an artificially chosen point offshore.2United Nations. United Nations Convention on the Law of the Sea
Where two countries face each other or share an adjacent coastline, their 200-mile claims often overlap. UNCLOS directs them to negotiate an “equitable solution” grounded in international law. If they cannot agree within a reasonable time, either side can invoke the treaty’s dispute resolution procedures, including arbitration or referral to the International Tribunal for the Law of the Sea or the International Court of Justice.1United Nations. United Nations Convention on the Law of the Sea – Part V – Exclusive Economic Zone In the meantime, both sides are expected to cooperate on provisional arrangements and avoid steps that would make a final settlement harder.
What the Coastal Country Controls
Inside the zone, a coastal nation has sovereign rights to explore, exploit, conserve, and manage every natural resource. That covers living resources like fish and shellfish, non-living resources like oil and gas trapped in the seabed, and energy drawn from the water itself through wind turbines, wave converters, and ocean current systems.1United Nations. United Nations Convention on the Law of the Sea – Part V – Exclusive Economic Zone “Sovereign rights” is a narrower idea than sovereignty over land. A country owns the fish and the oil, but not the water column the way it owns its territory.
Governments turn these rights into revenue by leasing blocks of seabed to private companies. A single U.S. Gulf of Mexico lease sale brought in more than $178 million in high bids across 144 tracts.3U.S. Department of the Interior. Interior Announces Results of Gulf of Mexico Region-Wide Oil and Gas Lease Royalties on production add ongoing revenue; U.S. rates run from 12.5 percent in shallower waters to 18.75 percent in deeper areas.4Bureau of Ocean Energy Management. BOEM Announces Oil and Gas Lease Sale for Gulf of Mexico
The coastal state also has the exclusive right to build and regulate artificial islands, offshore platforms, and other installations, and it may establish a safety zone of up to 500 meters around each structure.1United Nations. United Nations Convention on the Law of the Sea – Part V – Exclusive Economic Zone All vessels must respect those zones.
Foreign marine scientific research is a separate lever. Outside researchers need the coastal state’s consent before working in the zone, and that consent can be refused if the research directly relates to resource exploration or involves drilling, explosives, or the construction of structures.5United Nations. United Nations Convention on the Law of the Sea – Part XIII Marine Scientific Research Projects that stray from their approved terms can be suspended or shut down, and equipment usually has to come out at the end.2United Nations. United Nations Convention on the Law of the Sea
Environmental protection cuts both ways. UNCLOS obliges every nation to protect and preserve the marine environment, and within its zone the coastal state has jurisdiction to enforce rules against pollution from vessels, drilling, and installations. The duty extends beyond national waters: countries must make sure activities under their control do not send pollution into neighboring zones or onto the high seas, and they must notify affected states when serious harm is imminent.6United Nations. United Nations Convention on the Law of the Sea – Part XII
What Other Countries Can Still Do
The zone is not a private ocean. All nations keep the freedom of navigation, overflight, and the right to lay submarine cables and pipelines through another country’s zone.1United Nations. United Nations Convention on the Law of the Sea – Part V – Exclusive Economic Zone A cargo ship crossing between continents does not need permission to transit, and a commercial airliner does not need clearance to fly over. The coastal state cannot interfere with those freedoms as long as they do not clash with its resource rights.
Submarine cables get particular protection because they carry more than 95 percent of intercontinental data traffic. International law dating back to the 1884 Paris Convention makes it a punishable offense to break or damage a submarine cable through willful action or negligent seamanship. Cable owners who damage another company’s cable during their own installation must pay for the repairs, and a fishing vessel that sacrifices its nets to avoid snagging a cable is entitled to compensation from the cable’s owner.7National Oceanic and Atmospheric Administration. Submarine Cables – International Framework UNCLOS reinforced these protections on the continental shelf, with coastal states retaining only conditions tied to their own resource activities.
Fisheries and the Surprising Surplus Rule
UNCLOS does not simply hand over the fish. Each coastal nation must set an allowable catch that prevents overfishing and keeps stocks at levels able to produce a maximum sustainable yield, based on the best available science and taking account of species that depend on the harvested stock.1United Nations. United Nations Convention on the Law of the Sea – Part V – Exclusive Economic Zone
If a country cannot harvest its entire allowable catch with its own fleet, it is expected to grant foreign nations access to the surplus, with particular consideration for landlocked and developing countries in the same region.1United Nations. United Nations Convention on the Law of the Sea – Part V – Exclusive Economic Zone The rule keeps a nation from locking up marine resources it cannot use.
Countries translate these duties into domestic law. In the United States, the Magnuson-Stevens Act governs commercial and recreational fisheries within the zone. Federal regulators set annual catch limits for each managed species, and if final limits are delayed, default catch limits fill the gap. If even the defaults expire, fishing in the affected stock areas stops entirely until new limits take effect.8Federal Register. Magnuson-Stevens Act Provisions; Fisheries of the Northeastern United States; Northeast Multispecies Fishery; Allocation of 2026 Northeast Multispecies Annual Catch Entitlements and Notice of Default Specifications
Enforcement Powers and Their Limits
UNCLOS lets the coastal state board, inspect, and arrest foreign vessels that violate its fisheries laws inside the zone. Once a vessel is arrested, the state must promptly notify the vessel’s home country and release the ship and crew on a reasonable bond.1United Nations. United Nations Convention on the Law of the Sea – Part V – Exclusive Economic Zone
One notable ceiling: penalties for fisheries violations cannot include imprisonment or any form of corporal punishment unless the countries involved have a specific agreement allowing it.1United Nations. United Nations Convention on the Law of the Sea – Part V – Exclusive Economic Zone Financial penalties and equipment seizure are the standard tools. Coastal states get real leverage over foreign fleets, but they cannot jail foreign crews for what amounts to an economic offense.
In the United States, the Coast Guard is the lead federal agency for maritime law enforcement from inland waters through the entire zone, including interception of illegal foreign fishing vessels and compliance with the Magnuson-Stevens Act, the Endangered Species Act, and international fisheries agreements.9United States Coast Guard. Maritime Law Enforcement Program
Seabed Rights Beyond 200 Miles
The 200-mile line is not the end of a country’s seabed rights. Where the physical continental shelf runs past that distance, a coastal state can claim sovereign rights over the seabed and subsoil of the extended area. Those extended rights cover only the seabed and what lies beneath it, not the fish or other resources in the water above.10United States Department of State. About ECS
The outer edge of the extended shelf is set by ocean-floor geology rather than a flat number. UNCLOS gives two formulas: a country can draw its boundary where sedimentary rock thickness equals at least one percent of the distance back to the foot of the continental slope, or at fixed points no more than 60 nautical miles from that foot. Either way, the line cannot exceed 350 nautical miles from the coast or 100 nautical miles from the 2,500-meter depth contour, whichever is more favorable.11United Nations. Part VI Continental Shelf To lock in these rights, a country submits geological and geophysical data to the Commission on the Limits of the Continental Shelf. The Commission’s recommendations are not binding on their own, but shelf limits set on the basis of those recommendations become final and binding.12United Nations. Submissions to the CLCS
The Unresolved Military Question
UNCLOS deliberately sidesteps one question, and it has become the most contentious issue tied to these zones: whether foreign military forces can conduct surveillance, exercises, and intelligence-gathering inside another nation’s zone. The treaty guarantees “other internationally lawful uses of the sea” related to navigation and overflight, but it never spells out whether military activities qualify.1United Nations. United Nations Convention on the Law of the Sea – Part V – Exclusive Economic Zone
Most Western maritime powers, led by the United States, take the position that military operations have always been a lawful use of the seas and that UNCLOS preserves that right inside foreign zones. Countries like China counter that foreign surveillance flights and naval intelligence collection threaten peace and security and therefore violate the treaty’s requirement that states exercise their freedoms with “due regard” for the coastal state’s rights. Some go further, arguing that military data collection resembles marine scientific research and should require the coastal state’s consent. The disagreement is not academic; overlapping claims and military posturing have made the South China Sea one of the world’s most volatile maritime flashpoints.
Why the U.S. Position Is Unusual
As of February 2026, 172 nations have ratified UNCLOS.13United Nations. Chronological Lists of Ratifications The most conspicuous holdout is the United States, which signed the convention in 1994 but has never submitted it for Senate ratification. Even so, the U.S. established its own 200-mile zone in 1983 through Presidential Proclamation 5030, claiming sovereign rights over natural resources, jurisdiction over artificial structures, and authority to protect the marine environment in language that closely tracks UNCLOS.14National Archives. Proclamation 5030
The U.S. treats most of the treaty’s provisions on these zones as reflecting customary international law and follows them in practice. The practical result is that the world’s largest naval power operates under the framework while sitting outside the treaty system that governs it, which limits its participation in bodies like the Commission on the Limits of the Continental Shelf and its ability to invoke the treaty’s binding arbitration mechanisms.