The ocean floor has long been a subject of legal complexity, scientific fascination, and geopolitical tension. Beneath the waves, vast stretches of seabed extend from the coastlines of nations, rich with oil, gas, minerals, and marine biodiversity. These underwater territories—known as continental shelves—sit at the center of one of international law’s most consequential questions: who has the right to claim them, exploit them, and govern them?
The answer is far from simple. Continental shelf ownership is shaped by a layered framework of international treaties, customary law, and binding arbitration decisions. Understanding this framework matters not only for legal scholars and diplomats, but also for industries, coastal communities, and anyone with an interest in how the world’s natural resources are governed.
This article traces the legal foundations of continental shelf rights, explains how boundaries are determined, examines the role of key international institutions, and explores the disputes that continue to test the system today.
The Legal Foundation of Continental Shelf Rights
The modern legal concept of the continental shelf emerged in 1945, when U.S. President Harry Truman issued a proclamation asserting American jurisdiction over the natural resources of the seabed and subsoil of the continental shelf adjacent to U.S. coasts. Known as the Truman Proclamation, this unilateral declaration triggered a wave of similar claims from other coastal states and effectively launched the era of continental shelf law.
The first major multilateral response came with the 1958 Geneva Convention on the Continental Shelf, which recognized the sovereign rights of coastal states over their adjacent shelves for the purpose of exploring and exploiting natural resources. However, the convention’s definition of the shelf’s outer boundary—tied to the vague criterion of “exploitability”—proved inadequate as technology advanced.
The more definitive legal framework arrived with the United Nations Convention on the Law of the Sea (UNCLOS), adopted in 1982 and entering into force in 1994. UNCLOS is widely regarded as the constitution of the oceans. Today, 168 states and the European Union are parties to it, making it one of the most broadly ratified international treaties in history.
How UNCLOS Defines the Continental Shelf
Under UNCLOS, a coastal state’s continental shelf comprises the seabed and subsoil of submarine areas that extend beyond its territorial sea throughout the natural prolongation of its land territory. The standard entitlement extends to 200 nautical miles from the state’s baselines, regardless of whether the actual geological shelf reaches that distance.
This 200-nautical-mile zone corresponds to the Exclusive Economic Zone (EEZ), within which a state also holds sovereign rights over living and non-living resources. However, the continental shelf and the EEZ are legally distinct. The continental shelf relates specifically to the seabed and its subsoil, while the EEZ also covers the water column above.
Where the natural prolongation of the landmass extends beyond 200 nautical miles, a state may claim an extended continental shelf. UNCLOS Article 76 establishes detailed technical criteria for determining this outer boundary. These criteria involve the thickness of sedimentary rock layers, the distance from the foot of the continental slope, and maximum outer limits of 350 nautical miles from the baselines or 100 nautical miles from the 2,500-meter isobath—whichever is more favorable to the coastal state.
The Role of the Commission on the Limits of the Continental Shelf
The outer boundary of an extended continental shelf cannot be self-declared. Coastal states seeking to claim beyond 200 nautical miles must submit detailed scientific and technical data to the Commission on the Limits of the Continental Shelf (CLCS), a body established under UNCLOS and composed of 21 experts in geology, geophysics, and hydrography.
The CLCS reviews submissions and makes recommendations on where the outer limits should lie. Once a coastal state establishes its outer limits in conformity with these recommendations, those limits become final and binding under international law. As of 2024, the CLCS has received over 90 submissions from states around the world, with many still awaiting review due to the commission’s heavy workload.
It is important to note that the CLCS does not resolve overlapping claims between states—it only determines the outer limits relative to the deep seabed. Disputes between neighboring states over where one nation’s shelf ends and another’s begins fall outside the CLCS mandate and must be resolved through negotiation or judicial proceedings.
Sovereign Rights Versus Full Sovereignty
A critical distinction in continental shelf law is the difference between sovereign rights and full sovereignty. Coastal states do not own the continental shelf in the way they own their land territory. Instead, UNCLOS grants them sovereign rights for the purpose of exploring and exploiting its natural resources, including hydrocarbons, minerals, and sedentary species such as oysters and corals.
These rights are exclusive in nature. No other state may explore or exploit the resources of a coastal state’s continental shelf without its express consent. However, the rights do not affect the legal status of the superjacent waters or airspace above the shelf. Other states retain the freedom of navigation, overflight, and the laying of submarine cables and pipelines across the continental shelf—activities that full sovereign ownership might otherwise restrict.
This balance reflects a broader principle embedded in UNCLOS: the resources of the seabed belong to coastal states, but the ocean itself remains a global commons.
The Area Beyond National Jurisdiction
Beyond the outer limits of any national continental shelf lies the international seabed, formally referred to as “the Area” under UNCLOS. The Area and its mineral resources are declared the common heritage of mankind—a principle that means no state can claim sovereignty over them.
The International Seabed Authority (ISA), established under UNCLOS and headquartered in Kingston, Jamaica, governs all mineral-related activities in the Area. The ISA issues exploration and exploitation contracts to both state-owned enterprises and private companies, ensuring that the benefits of deep-sea mining are shared internationally, particularly with developing nations.
The common heritage principle represents one of international law’s most ambitious experiments in global governance. Its practical application, however, has been contested. Developed nations with the technological capacity for deep-sea mining have at times pushed for frameworks that allow greater commercial freedom, while developing nations have advocated for stronger revenue-sharing mechanisms.
Major Continental Shelf Disputes and Their Resolution
Despite UNCLOS providing a widely accepted legal framework, continental shelf disputes remain a persistent feature of international relations. Several high-profile cases illustrate the complexities involved.
In the Arctic, five coastal states—Russia, Canada, the United States, Norway, and Denmark (on behalf of Greenland)—have overlapping claims to the extended continental shelf. Russia’s 2001 submission to the CLCS, which sought to claim a vast portion of the Arctic seabed including the Lomonosov Ridge, was sent back for revision and resubmitted in revised form in 2015. Canada and Denmark have made competing submissions for portions of the same ridge. These overlaps will ultimately require bilateral negotiations or international arbitration to resolve.
The South China Sea presents a different and more politically charged scenario. China has advanced extensive claims over the seabed and resources of the South China Sea based on historical grounds, encapsulated in the so-called “nine-dash line.” In 2016, an arbitral tribunal constituted under UNCLOS Annex VII ruled, in the case brought by the Philippines, that China’s historical claims had no legal basis under UNCLOS. China rejected the ruling, and the dispute remains unresolved, continuing to be a flashpoint for regional tension.
In contrast, the maritime boundary delimitation between Bangladesh, Myanmar, and India in the Bay of Bengal resulted in landmark decisions by the International Tribunal for the Law of the Sea (ITLOS) and the International Court of Justice (ICJ), which applied equidistance principles adjusted by relevant circumstances to delineate overlapping continental shelf claims—providing a model for peaceful dispute resolution.
The Growing Importance of Deep-Sea Resources
Continental shelf ownership has taken on new dimensions as the commercial viability of deep-sea resource extraction increases. Hydrocarbons have long been the primary driver of shelf-related disputes and development. The world’s largest offshore oil and gas fields—located in the Gulf of Mexico, the North Sea, the Persian Gulf, and the Brazilian pre-salt basin—sit within national continental shelf zones and generate trillions of dollars in revenues annually.
Beyond hydrocarbons, the seabed contains polymetallic nodules, cobalt-rich crusts, and seafloor massive sulfide deposits that hold significant quantities of nickel, cobalt, manganese, copper, and rare earth elements. As demand for these materials grows—driven by the energy transition and the expansion of battery technology—the commercial and strategic value of continental shelf rights will only intensify.
Environmental considerations add another layer of complexity. Deep-sea ecosystems are among the least understood and most fragile on Earth. The exploitation of continental shelf and deep-sea resources raises profound questions about environmental stewardship, and international law is increasingly grappling with how to balance resource rights with the obligation to protect the marine environment.
The Ongoing Evolution of Continental Shelf Law
International law governing the continental shelf is not static. The 2023 adoption of the Agreement on the Conservation and Sustainable Use of Marine Biological Diversity of Areas Beyond National Jurisdiction (the BBNJ Agreement, also known as the “High Seas Treaty”) marks a significant development. While focused primarily on biodiversity rather than resource rights, the treaty creates new governance mechanisms for the high seas and reflects a growing international consensus that ocean governance must adapt to contemporary challenges.
Meanwhile, the work of the CLCS continues to reshape the map of national continental shelf entitlements. As more submissions are processed and recommendations issued, the legal boundaries of coastal state jurisdiction are being drawn with increasing precision—often after decades of scientific survey and diplomatic negotiation.
A Framework Built on Shared Responsibility
Continental shelf ownership is neither absolute nor arbitrary. It operates within a carefully constructed international framework designed to balance the legitimate resource interests of coastal states with the broader principle that the oceans are a shared global resource.
UNCLOS remains the cornerstone of this framework, providing coastal states with clearly defined rights while placing those rights within a system of international obligations and oversight. Disputes will continue to arise—driven by overlapping geography, competing resource interests, and geopolitical rivalries—but the legal architecture for managing them is more developed today than at any previous point in history.
For policymakers, industry stakeholders, and legal practitioners, understanding who owns the continental shelf means understanding not just the rights it confers, but the responsibilities those rights carry. The seabed is not merely a resource base—it is a governance challenge that will define how nations cooperate, compete, and coexist in the decades ahead.