# Law of the Sea Who owns the ocean? For most of human history the answer was straightforward: nobody, or everybody. The Dutch jurist Hugo Grotius articulated the doctrine of mare liberum — freedom of the seas — in 1609, arguing that the ocean was international territory open to all nations for navigation and fishing. That principle held for centuries. But as technology made it possible to extract resources from the seabed, fish stocks faced depletion, and naval competition intensified, the need for a comprehensive legal framework became unavoidable. The result was the United Nations Convention on the Law of the Sea (UNCLOS) — the most ambitious attempt in history to govern two-thirds of Earth's surface. ## UNCLOS UNCLOS was adopted in 1982 and entered into force in 1994. It establishes a nested system of maritime zones radiating outward from a nation's coastline. Territorial waters extend 12 nautical miles from the baseline — within this zone, the coastal state exercises full sovereignty, subject to a right of innocent passage for foreign vessels. The contiguous zone extends to 24 nautical miles, where states can enforce customs, immigration, and sanitary regulations. The exclusive economic zone (EEZ) extends to 200 nautical miles from the baseline. Within the EEZ, the coastal state has sovereign rights over natural resources — fish, minerals, energy — but other nations retain freedoms of navigation and overflight. The continental shelf, where it extends beyond 200 miles (as determined by geological criteria), can give coastal states resource rights over the seabed out to 350 nautical miles or beyond. Beyond national jurisdiction lies the high seas — roughly 64% of the ocean surface — and the deep seabed, which UNCLOS designates as the "common heritage of mankind," administered by the International Seabed Authority. The high seas remain governed by the freedom of the seas principle: open to all nations for navigation, fishing, scientific research, and cable laying. The United States has not ratified UNCLOS — one of the few major nations that hasn't — despite the fact that the U.S. Navy treats UNCLOS as customary international law and conducts freedom of navigation operations based on its provisions. Opposition to ratification comes primarily from Republican senators who object to the International Seabed Authority's regulatory authority and to any treaty perceived as constraining U.S. sovereignty. This creates the paradox of the world's most powerful navy enforcing a treaty its own government hasn't formally accepted. ## The South China Sea The most dangerous maritime dispute in the world centers on the South China Sea, where [[China]] claims sovereignty over roughly 90% of the sea based on a "nine-dash line" that has no basis in UNCLOS and was rejected by a 2016 arbitral tribunal ruling under the Permanent Court of Arbitration. China has refused to recognize the ruling — a wholesale rejection of the international legal order governing the oceans. China has constructed artificial islands on submerged reefs in the Spratly and Paracel Islands, building military installations including airstrips, radar facilities, and missile batteries on features that were previously underwater at high tide. Under UNCLOS, artificial islands do not generate territorial waters or EEZ claims, but China's physical presence creates facts on the ground (or rather, on the water) that are difficult to reverse. The stakes are enormous. The South China Sea carries roughly one-third of global shipping by value. Its seabed may contain significant oil and gas reserves. The fisheries feed hundreds of millions of people across Southeast Asia. The Philippines, Vietnam, Malaysia, Brunei, and Taiwan all have competing claims that overlap with China's maximalist position. The [[United States Navy]] conducts regular freedom of navigation operations through disputed waters, sailing warships within 12 nautical miles of Chinese-occupied features to assert that these constructions do not create legal territorial claims. ## Arctic Claims As Arctic ice retreats due to warming documented by [[Glaciology]], the five Arctic coastal states — Russia, Canada, the United States, Norway, and Denmark (via [[Greenland]]) — are filing continental shelf claims with the Commission on the Limits of the Continental Shelf, seeking to extend their seabed resource rights across the Arctic Ocean. [[Russia]] has claimed a vast swath of the Arctic seabed by arguing that the Lomonosov Ridge — an undersea mountain range running from Siberia past the North Pole to Greenland — is a geological extension of the Russian continental shelf, a claim explored in depth in [[Arctic Geopolitics]]. The melting Arctic also raises questions about navigation rights. [[Russia]] claims the Northern Sea Route as internal waters requiring Russian permission for transit — a claim the United States and European nations reject, insisting on freedom of navigation under UNCLOS. This legal dispute is inseparable from the military and economic competition playing out across the Arctic. ## Freedom of Navigation Freedom of navigation — the principle that warships and commercial vessels can transit through international waters without interference — is the bedrock of the rules-based maritime order and a core mission of the [[United States Navy]]. The U.S. Navy's Freedom of Navigation Program, established in 1979, conducts operational challenges to excessive maritime claims worldwide — not just China's. The program has challenged claims by allies and adversaries alike, asserting that the legal principles matter regardless of who violates them. The tension between freedom of navigation and coastal state sovereignty is sharpest at maritime chokepoints — narrow passages where global shipping must transit. The Strait of Hormuz (20-30% of global oil trade), the Strait of Malacca (roughly 25% of all traded goods), the Suez Canal, and the [[Bab el-Mandeb]] strait are all governed by UNCLOS transit passage provisions that guarantee unimpeded passage. Control or disruption of any of these chokepoints can reshape global trade and energy markets, as the Houthi attacks on Red Sea shipping demonstrated in 2023-2024. ## See Also - [[China]] — South China Sea claims and artificial island construction - [[Russia]] — Arctic claims and Northern Sea Route disputes - [[United States Navy]] — freedom of navigation operations - [[Greenland]] — Arctic sovereignty and continental shelf claims - [[Arctic Geopolitics]] — resource competition in the melting Arctic - [[NATO]] — alliance maritime security coordination