On October 17, 2024, two Chinese coast guard cutters entered port in Zhoushan, an island harborage south of Shanghai. The vessels, the Meishan and the Xiushan, were returning from an extraordinary journey. Traditionally, China was not a major seafaring nation. During the fifteenth century, Admiral Zheng He famously led several “treasure voyages” as far as the Indian Ocean coast of Africa.Footnote ¹ Yet Ming Dynasty leaders soon put a stop to such distant seaborne exploration. The reasons are disputed by historians, but over the ensuing centuries Chinese ships rarely strayed from the Western Pacific.

In recent decades a vast new armada of Chinese ships has crisscrossed the world’s oceans, laden with a modern type of treasure in the form of massive stacks of containers brimming with inexpensive goods. The Meishan and the Xiushan, however, were not on a commercial voyage. Nor were they closely plying China’s offshore waters. Rather, the coast guard cutters were returning to port from a tour of the distant Arctic Ocean. The Meishan and the Xiushan sailed to and traversed the Arctic accompanied by ships of a seasoned Arctic power: Russia. The Chinese ships first sailed to Vladivostok, Russia’s easternmost city.Footnote ² Then, after a joint patrol of the Northern Pacific, the combined Russian-Chinese fleet headed for the far-off Bering Strait.

China’s territory is not close to the Arctic. Its northernmost prefecture, Da Hinggan Ling, is at about the same latitude as Berlin. Yet China has recently declared itself to be a “near Arctic state.”Footnote ³ That designation, an invention of Beijing, reflects the growing importance of the Arctic Ocean in a warming world. The Arctic has long been an alluring yet dangerous passageway around the Northern Hemisphere, one often impossible to traverse due to ice. Scientists now believe it may have its first ice free day as early as 2027.Footnote ⁴ The expanded access the accelerating climate crisis creates has made the Arctic a more realistic shipping zone, and hence a domain of ever-greater strategic and economic importance.

Asked about the 2024 voyage to the Arctic, a Chinese military leader stated that the coast guard “had demonstrated its ability to protect maritime transport in the region.”Footnote ⁵ For at least a decade China has described its overall naval strategy as one of “near seas defense and far seas protection.”Footnote ⁶ China’s desire for “far seas protection” stems from its growing economic dynamism. The workshop of the world, China’s ships and goods ply the oceans in huge quantities. Beijing’s rising political and military aspirations have led it to seek port arrangements in distant territories. And as its wealth and size have swelled, China’s vast fishing fleets have increasingly peregrinated from the mainland in search of new catches.

All this maritime activity necessitates ever greater “far seas protection.” The unusual voyages of the Meishan and the Xiushan suggest that Beijing believes the volume of shipping to be protected in the Arctic will grow rapidly as well. Indeed, China might be said to be echoing the thinking of America’s most famous maritime theorist. The Influence of Sea Power Upon History: 1660–1783, Alfred Thayer Mahan’s influential 1890 treatise, argued that naval reach flowed from commercial reach. The “necessity of a navy,” Mahan wrote, springs “from the existence of a peaceful shipping, and disappears with it.”Footnote ⁷ (He then added an important caveat: “except in the case of a nation which has aggressive tendencies, and keeps up a navy merely as a branch of the military establishment.”)Footnote ⁸

In Near and Far Waters: The Geopolitics of Sea Power (2024), Colin Flint, a professor of geography, describes how states throughout history have progressed from a focus on near waters to rising attention to distant seas.Footnote ⁹ The central argument of the book is that sea power is “an ever-changing struggle to gain control of near or far waters” (Flint, p. 2). Near and far waters, Flint contends, are “fuzzy areas;” they are defined by the actions and preferences of states, “not by lawyers” (Flint, p. 10). Yet international law plays a vital framing role in this dichotomy. Flint defines near waters as those falling within the exclusive economic zone of a coastal state. An exclusive economic zone is an area established under the United Nations Convention on the Law of the Sea as “beyond and adjacent to the territorial sea” and extending a maximum of 200 nautical miles from shore.Footnote ¹⁰

Far waters may of course be someone else’s near waters. China’s newfound interest in Arctic far waters means Chinese ships may increasingly be found in the near waters of existing coastal powers, such as Canada, Norway, and the United States. More often, far waters are simply very distant from land and under no nation’s jurisdiction. Called the void spaces of the Earth by the Antarctic explorer Ernest Shackleton, the far waters of the world are massive in scale.Footnote ¹¹

These far waters are not only huge; they also interconnected. In The Free Sea: The American Fight for Freedom of Navigation (2018), James Kraska and Raul Pedrozo explain that sea power “exploits the physical fact of the global ocean’s unity” (Kraska & Pedrozo, p. 2).Footnote ¹² While control of such an immense realm is always tenuous, both Flint and Kraska and Pedrozo argue that sea power has long conferred great strategic advantages back on land, where humanity actually resides and governs. The Influence of Sea Power Upon History, written as the United States was just beginning its wave of overseas expansion, is perhaps the most famous exposition of the view that sea power is crucial to land power. But in many respects Mahan, who wrote his masterwork when he was president of the Naval War College, detailed what had long been understood in a more instinctive way: whoever rules the waves rules the world.Footnote ¹³

Lasting wealth and power may not depend on the control of the seas, but sea power certainly offers a very attractive and effective path. Who wields that important power can in turn shape how power itself is wielded. Throughout history, The Free Sea declares, “political order largely has been an outgrowth of the sea as a vector for transit” (Kraska & Pedrozo, p. 2). By allocating access to the oceans and their resources, the law of the sea acts as an important regulator and shaper of sea power—and therefore of global order more generally.

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Flint’s and Kraska and Pedrozo’s books, alongside the others discussed in this essay—Sugata Bose’s A Hundred Horizons: The Indian Ocean in an Age of Empire (2006) and Ian Urbina’s The Outlaw Ocean: Journeys Across the Last Untamed Frontier (2019)—reflect renewed interest in the political and historical dimensions of the oceans and, consequently, in the laws governing them. The law of the sea has a venerated status among international lawyers. First published in 1609, Grotius’s Mare Liberum, or “Free Sea”—whose title Kraska and Pedroza deliberately crib—is a justifiably foundational text in the history of the international law.Footnote ¹⁴ Grotius took a Roman concept and updated it for a new age of maritime competition. In the centuries since, the law of the sea has markedly expanded in scope and significance. This process has accelerated in the twenty-first century, transforming a sometimes-dusty and arcane field to one that increasingly consumes the attention of political leaders and legal experts alike. The rapidly growing naval power of China is a large part of that shift, in particular because of Beijing’s controversial—Kraska and Pedrozo call it “audacious”—pursuit of claims in the highly-strategic South China Sea (Kraska & Pedrozo, p. 264). But a series of other events, ranging from the nearly week-long closure of the Suez Canal in 2021 (stemming from the grounding of a huge container vessel, the Ever Given)Footnote ¹⁵ to the recent “Red Sea Crisis” sparked by Houthi attacks on shipping lanes near Yemen,Footnote ¹⁶ have all thrust the maritime domain deeper into the global spotlight.

The high seas occupy an unusual place within the international legal order. For at least a century, all of the Earth’s land surface—save Antarctica—has fallen within the territorial borders of one or another sovereign state. The seas constitute a vast reserve from this regime of territorial sovereignty: a largely common space still wild, yet full of coveted and often shrinking resources. The oceans have long served as essential trade highways, means of conquest, and sources of wealth and sustenance. For millennia they have linked peoples and created regions through which cultures, goods, and migrants flowed. The oceans are, in essence, an open highway to every coastal state, bearing on its surface all the goods—and ills—of the wider world.

The subject of centuries of attention from lawyers, there is, as a result, a rich body of law governing the oceans. From Grotius through famed early cases such as the Paquete Habana Footnote ¹⁷ and the Lotus,Footnote ¹⁸ maritime law long looked to custom as its primary source of rules. This corpus of customary law remains significant. Yet since 1994 it has been blanketed by an intricate, exhaustive treaty regime, the 1982 UN Convention on the Law of the Sea. Comprising over 300 discrete articles and nine annexes, the convention is commonly known as UNCLOS. UNCLOS is a landmark not only for its scale and scope—over a decade of complex negotiations involving thousands of participants—but also because it is an exemplar of the postwar effort to codify and refine international law through multilateral processes centered around the United Nations.

The UNCLOS negotiators built heavily on custom, but also looked to earlier high seas treaties, in particular the four conventions signed in 1958 sometimes referred to as the Geneva Conventions on the Law of the Sea.Footnote ¹⁹ They aimed to rationalize the law of the sea as it stood in the heart of the Cold War. Yet many participants also sought to reflect the changing reality of a globe that had, strikingly, transitioned in a matter of two decades from a world of empires to one of sovereign states. The International Court of Justice famously wrote in the 1969 North Sea Continental Shelf judgment that “the land dominates the sea.”Footnote ²⁰ By this the Court meant that that maritime rights flow from sovereignty over adjacent land. It was, as a result, perhaps inevitable that the powerful wave of decolonization that crested in the 1960s, and thoroughly redrew the world’s land borders, would work important changes into the fabric of the law of the sea as well.

Few had imagined how rapidly decolonization would unfold, nor how dramatically it would reshape world politics. When the iconic United Nations headquarters were first proposed in 1947, the organization comprised fifty-five states. In designing the buildings, the UN leadership considered what size campus would be sufficient for the likely growth of the organization. The answer was to plan for about seventy-five member states.Footnote ²¹ This, of course, proved a gross understatement. By 1970, the year the General Assembly declared the seabed to be the common heritage of mankind,Footnote ²² the UN had grown to 127 members. (Today it stands at 193.)Footnote ²³ In short, in less than a quarter century the global order was transformed by a rush of new states. This was a triumph—one at times joyful, liberatory, and violent—for justice and self-determination. It also thoroughly recast the composition of the UN. The varied new states, many of whom had long experience with the oceans but had played no role in the slow, centuries-long accretion of the customary law of the sea, wanted a chance to refine those rules and rebalance their equities. The result was a sprawling, years-long conclave that produced one of the most significant treaties of the post-war era.

UNCLOS has rightly been termed the “constitution of the oceans.”Footnote ²⁴ Its text covers nearly every imaginable issue; provisions range from the role of river mouths in the demarcation of the territorial sea to the rules governing ships that fly the flag of the UN itself. That the negotiations took place in the middle of the Cold War had implications as interesting as those resulting from decolonization. The 1970s were a time when the law of the sea was, perhaps paradoxically, an arena of both competition and cooperation for the two superpowers. Both sides used their large navies as a key source of power projection in a global war with no borders. As a result, they both shared an interest in maximally open access to the oceans.

The United States and the Soviet Union often worked in tandem on UNCLOS, Kraska and Pedrozo explain in The Free Sea, their history of American attitudes and actions to define and bolster the law of the sea. The Free Sea’s core argument is that freedom of navigation “has been and remains essential to American economic prosperity and strategic security” (Kraska & Pedrozo, p. 1). The Soviet Union, a land-based power that was always more economically isolated than the United States, nonetheless shared its rival’s strategic and security interests in freedom of navigation—especially since it lacked extensive access to warm-water ports.

During UNCLOS, both superpowers sought to “enshrine broadly unrestrictive rules for freedom of navigation and overflight” (Kraska & Pedrozo, p. 4).Footnote ²⁵ A central example was the right of warships to engage in innocent passage without notification of the coastal state. Innocent passage occurs when a vessel traverses a territorial sea in a manner that is “not prejudicial to the peace, good order or security” of the coastal state.Footnote ²⁶ Debated widely in the negotiations, this issue was particularly important to the Soviets, who lacked convenient access to the high seas from ports such as Sevastopol on the Black Sea (Kraska & Pedrozo, p. 230). Kraska and Pedrozo argue the Soviet Union was “not above scoring diplomatic points” with the post-colonial world in the UNCLOS process (Kraska & Pedrozo, p. 230). Yet on this critical issue, it sided with its arch enemy and secured broad transit rights.

While the superpowers successfully imposed their preferences on UNCLOS regarding their core national security concerns, the post-colonial states had greater success regarding the emerging economics of the law of sea. The negotiations reflected the desire of many new states to redistribute the economic value that flows from access to and control over the oceans.

The concept of an exclusive economic zone, for instance, had been pressed by various states before, particularly in Latin America.Footnote ²⁷ But it was UNCLOS that fully developed this concept in international law. The Free Sea argues that the exclusive economic zone, or EEZ, was devised “for the sole purpose of granting coastal states control over the living and nonliving resources adjacent to their coasts” (Kraska & Pedrozo, p. 248). Much of the intensifying maritime conflict between the United States and China in recent years, Kraska and Pedroza aver, results from expansive Chinese views about the rights commensurate with an EEZ. (China was an early proponent of UNCLOS’ EEZ regime, seeing it as essential to the developing world’s struggle against the “super-power maritime hegemony” of the time.)Footnote ²⁸ Unlike in the twelve-mile-wide territorial sea, where states exercise sovereignty akin to their land territory, coastal states exercise only “sovereign rights” in an EEZ.Footnote ²⁹ China, The Free Sea insists, takes a more aggressive stance, one the United States is rightly resisting.Footnote ³⁰

While issues of freedom of navigation were and remain centrally important to major naval powers, for many states, the EEZ is fundamentally an economic asset. The cementing of the EEZ in UNCLOS carved up a much larger portion of the oceans for economic exploitation and effectively shrunk the common space of the globe. A number of archipelagic states, such as Indonesia and the Philippines, gained massively from this development. So too did small island states, which often secured outsized control over the economic resources of the ocean. Palau, for instance, a state with a population of less than 20,000, has an EEZ that covers nearly 250,000 square miles—an area almost the size of Texas. But perhaps critical to the success of this doctrinal revolution was the fact that the great powers, nearly all of whom have large coastlines and many islands, also gained substantially. The largest aggregate EEZs, indeed, are controlled by France and the United States.Footnote ³¹

Concern with equity and redistribution was most apparent in the protracted debate over deep seabed resources—an issue, long moribund, that has been rising in salience in recent years and was thrust to the headlines in 2025 by the Trump administration’s decision to unilaterally issue licenses for undersea mining.Footnote ³² When the UNCLOS process commenced in the 1970s, the ocean floor had long been largely inaccessible. But its potential riches were already alluring. A century earlier, while attempting to map the seafloor, the British ship HMS Challenger had dredged up some potato-sized nodules.Footnote ³³ They turned out to be full of valuable minerals.

In the 150 years since the HMS Challenger’s voyage, the appeal of seabed “mining” has only grown. Yet the extreme depth and pressure of the ocean floor meant that little actual mining had occurred as the UNCLOS negotiators considered the legal status of the seabed. There were few existing rules governing the seabed. As a result, a novel set of regulations could be hammered out without navigating around, as it were, the shoals of existing law. The fundamental question was the status of the resources of the deep. Were they open and appropriable to all comers who could find them? Or were they instead jointly owned, and therefore jointly regulable, by the international community?

In 1970, as these negotiations were just beginning, a U.S. firm called Deepsea Ventures began testing a vacuum-like technology off the coast of North Carolina. Concerned about the strength of its legal claim to the minerals it might soon capture in huge numbers, in 1974 the company sent a letter to National Security Advisor Henry Kissinger seeking support.Footnote ³⁴ To bolster its case, Deepsea Ventures quoted a young Charles Brower, then legal adviser at the State Department, who had asserted in a 1973 congressional hearing that under international law the resources littering the sea floor were “open to anyone who has the capacity to engage in mining.”Footnote ³⁵

The early 1970s were a time of technical and scientific optimism in the United States. This was the era of the U.S. space program and its multiple landings on the Moon that riveted the world.Footnote ³⁶ American technology was triumphant, and global commons from the seafloor to the distant cosmos seemed to be rapidly coming within the reach of sovereign and private claims. The United States, as a result, very much preferred that access to the deep seabed remain a high seas freedom; in any new gold rush, Americans were likely to lead the way.

Others around the world had different ideas. The early 1970s were the beginning of the effort to forge a “New International Economic Order.” As the euphoria of political liberation began to fade, many post-colonial states found they remained tied down by economic shackles imposed by the West. OPEC’s 1973 oil embargo suggested a path forward via collective action. The UN General Assembly, now heavily populated by newly independent states, was an attractive venue for exercising power in numbers. In the words of the iconic 1974 General Assembly declaration of the same name, the New International Economic Order would be based on principles of

The contemporaneous UNCLOS negotiations offered an opportunity to install similar principles. The goal was to forestall a race to exploit the undersea resources—one the West would surely dominate—and instead find a way to share those resources in an equitable manner.

Deepsea Ventures never successfully commercialized its technology. (Seabed mining would remain largely conjectural for decades.) But as UNCLOS unfolded, few predicted that undersea mining would remain so elusive. Indeed, mining was thought to be so imminent that in the 1970s the Central Intelligence Agency (CIA) successfully used it as cover for a remarkable covert operation to raise a sunken Soviet submarine off the seafloor near Hawaii. The CIA approached reclusive billionaire Howard Hughes to build a ship large enough to surreptitiously raise the submarine from 16,500 feet under the surface. The resulting Glomar Explorer was publicly billed as an innovative seabed mining vessel—until thieves, seemingly at random, broke into Hughes’s offices in Los Angeles and stole top secret documents detailing the cover story. The story eventually made its way to the Los Angeles Times, and the clandestine mission was over.Footnote ³⁸ Prior to this freak revelation, the Glomar Explorer even appeared in congressional hearings as evidence of the seemingly hurtling advance toward seabed extraction. When the question of mining technology was raised in 1973, a representative of the Nixon administration testified that despite the “uncertain legal situation,” investment of a “very substantial nature” was ongoing; the Hughes company, he noted, had already spent $50 million ($360 million today) “simply to develop their mining recovery ship.”Footnote ³⁹

To ensure that this new El Dorado would not simply become the property of the rich and powerful states, the UNCLOS negotiators proposed an International Seabed Authority (ISA). The ISA would possess jurisdiction over deep-sea resources. In particular, the seabed—referred to in the treaty as “The Area”—was declared to be the common heritage of mankind. (The Moon Treaty, which began negotiations in 1972, used the same term.)Footnote ⁴⁰ The common heritage concept, today widely deployed in many areas of international law, became a key part of the redefinition of the law of the sea that many states sought to work.Footnote ⁴¹ This approach to benefit-sharing was, unsurprisingly, controversial in Washington. Unlike the enshrinement of the EEZ, there was little for the United States to gain from such a collective and redistributive approach to deep sea resources. To conservatives, it was simply a witch’s brew of socialism, globalism, and big government. Indeed, it was one of the chief reasons then-President Ronald Reagan ultimately refused to sign UNCLOS in 1982.Footnote ⁴²

More than four decades later these rules continue to generate controversy. Despite the establishment in 1994 of the International Seabed Authority in Kingston, Jamaica, as of this writing, no commercial-scale seabed mining has ever taken place.Footnote ⁴³ Nor has the ISA issued the permits, let alone the rules governing permits, to do so.Footnote ⁴⁴ Yet with the huge global rise in demand for electric vehicles, mining these seafloor nodules, which contain key critical minerals used in batteries, has become far more attractive. Circumventing the slow-moving UNCLOS process, in April 2025 President Donald Trump signed an executive order instructing the National Oceanic and Atmospheric Administration (NOAA) to expedite permits to mine the seabed.Footnote ⁴⁵

Alarmed, the ISA responded that any unilateral mining would constitute a violation of international law. Moreover, it argued, the U.S. decision would “directly undermine the fundamental principles of multilateralism, the peaceful use of the oceans and the collective governance framework established under UNCLOS.”Footnote ⁴⁶ China—alongside Norway, India, and other states—agreed.Footnote ⁴⁷ Beijing argued that the seabed is the common heritage of humankind (a stance it had articulated as far back as the UNCLOS negotiations) and unilateral action plainly violates international law, positions likely not unrelated to the Trump administration’s stated goal to “get ahead of China in this resource space under the ocean.”Footnote ⁴⁸

The U.S. decision to issue mining licenses raises interesting interpretive questions. The United States is a signatory to UNCLOS—the Clinton administration signed the agreement in 1994—but it is not a party.Footnote ⁴⁹ U.S. officials have often stated, however, that UNCLOS is largely reflective of customary international law. At the fortieth anniversary of the signing of UNCLOS, for instance, the Biden administration declared that it was the “continued view” of the United States that “much of the convention reflects customary international law.”Footnote ⁵⁰ Kraska and Pedrozo, both professors at the U.S. Naval War College, generally concur. After the UN Charter, they write in The Free Sea, UNCLOS is the most comprehensive agreement in existence, and it “manifestly captures the historical rules of customary law and legal doctrine concerning freedom of navigation and overflight at sea” (Kraska & Pedrozo, p. 6).

The caveats in this statement, of course, say a lot. The Trump administration may argue that whatever rules UNCLOS contains on the deep seabed, they apply to the parties only; they have simply not reached the status of custom. And it may also choose to point to existing legislation, actions, and statements to attempt to support the notion that the United States is a persistent objector to any putative rule of custom governing the deep seabed.Footnote ⁵¹

As of this writing, however, and keeping with its general disdain for international law, the Trump administration has offered little support for its executive order beyond the Deep Seabed Hard Minerals Resources Act. (The 1980 statute was passed as an interim measure amid UNCLOS’ negotiation.)Footnote ⁵² But as was correctly noted by the first Trump administration, such a unilateral approach has important limits. “Any rights a U.S. company may have domestically,” NOAA stated in 2017, “are not secured internationally because U.S. companies are not able to go through the internationally recognized process at the International Seabed Authority” established by UNCLOS.Footnote ⁵³

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All of this might suggest that from the surface to the seabed, the oceans are awash in law. Yet in the view of some, they remain disturbingly lawless. That is the central thesis of The Outlaw Ocean, Ian Urbina’s 2019 exposé of the hidden reality of life at sea. Written while Urbina was a New York Times reporter, the book opens with an unsettling account of Cambodian “sea slaves,” young boys and men who have been coerced or compelled to work in horrific and even deadly conditions on Thai fishing vessels. Urbina describes the desperation—and deception—that leads many young Cambodians, who often have never seen the ocean before, to head out in unsafe and at times barely seaworthy vessels.

Even when not forcibly held on board, fisherman on the high seas face immense risks. Pervasive physical peril haunts the oceans; stultifying boredom and often extremely close quarters have long conspired to make the experience difficult and dangerous. (The eighteenth century English writer Samuel Johnson referred to a ship as “a jail, with a chance of being drowned.”)Footnote ⁵⁴ The contemporary human rights abuses Urbina documents onboard are shocking, and they are largely, he argues throughout the book, the result of the inherently under-policed nature of the vast ocean, where jurisdictional loopholes and sheer distance render the seas, to use his subtitle, the “last untamed frontier.”Footnote ⁵⁵

These observations are important, if not entirely new. Herman Melville, in Moby Dick, arrestingly describes Starbuck considering the murder of Ahab. “The land is hundreds of leagues away,” Starbuck thinks, “and locked Japan the nearest. I stand alone here upon an open sea, with two oceans and a vast continent between me and law.”Footnote ⁵⁶ Urbina’s title nonetheless reflects that law does exist at sea; it is simply often un- or under-enforced. (The book is The Outlaw Ocean, not The Lawless Ocean; while alliterative, it also reflects that Urbina’s central theme is the fundamental lack of enforcement at sea.)

Urbina’s focus is more often uncovering violations of the law rather than identifying lacunae in it. As he stresses, the problem of enforcement at sea is not limited to human rights. Some 40 percent of the global ocean catch is believed to be unreported; one in every five servings of fish is caught illegally.Footnote ⁵⁷ Rampant overharvesting is taxing many traditional fisheries, and even some that are untraditional. The fierce-looking Patagonian toothfish was once treated as bycatch. But after the FDA in 1994 accepted the name Chilean sea bass as an alternative, demand soared.Footnote ⁵⁸ While the toothfish population has somewhat stabilized, rogue trawlers still prowl the icy Antarctic waters. Likewise, piracy, an ancient scourge of the sea, remains a threat off the coast of places such as the Horn of Africa and the Gulf of Guinea. Drug trafficking, and a host of other smuggling activities, are carried out in small, unsafe boats and even jerry-rigged submarines.Footnote ⁵⁹ The law of the sea may be comprehensive, but it also provides, in Douglas Guilfoyle’s arresting phrase, “great thickets of law in which bad actors may hide.”Footnote ⁶⁰

Urbina, like many non-lawyers, sees less a thicket than a clearing. For all its breathtaking beauty, he writes,

Much of Urbina’s pessimism flows from a basic physical fact: the oceans are immense. Oceans cover some 140 million square miles of the planet, with an average depth of 12,000 feet. (The entire land territory of the Earth, even inclusive of vast and largely unpopulated deserts, tundras, and steppes, is less than half that size.) Only a quarter of the seafloor has ever been mapped.Footnote ⁶¹ Urbina rightly calls this the “least policed realm on the planet” (Urbina, p. 204). Even the portions of the ocean falling for at least some purposes within national jurisdiction, such as within an EEZ, are often too large to realistically chart or patrol. “Small land, big ocean” says the president of Palau, as he shows Urbina a map of the surrounding region (Urbina, p. 53).

The very scale of the oceans, however, is what gives them their special ability to link and even integrate disparate regions, peoples, and states. In A Hundred Horizons: The Indian Ocean in an Age of Global Empire (2006), Sugata Bose, a historian, weaves together a series of extended meditations on the Indian Ocean as an inter-regional and intercultural space—one that intertwined a diverse world, comprising South Asia, the Middle East, and East Africa.Footnote ⁶² The chief theme of A Hundred Horizons is the enduring “relevance and resilience of the Indian Ocean space in modern times” (Bose, p. 272). The Indian Ocean system has an ancient pedigree. But as Bose’s subtitle makes plain, the incursion of a dynamic West proved central to its historical trajectory. Expansive colonialism slowly turned the wide and warm ocean into a “British lake” (Bose, p. 274).

The British first arrived in corporate form—the East India Company—by, of course, the sea. From small outposts on the Bay of Bengal the East India Company’s power steadily grew. By the eighteenth century it effectively ruled large parts of India, using what Colin Flint in Near and Far Waters calls “sea lines of control” (Flint, pp. 19–20). These are essentially heavily trafficked oceanic routes that function as maritime highways. And they allowed Britain to readily project power and influence from London, thousands of miles away on a distant, chilly island. By the dawn of the nineteenth century, Britain was, in Kraska and Pedrozo’s terms, “the unchallenged global sea power” (Kraska & Pedrozo p. 57). Mastery of the seas allowed Britain to dramatically expand its sway throughout the Indian Ocean.

The British Raj ran right up to, and through, World War II. As Bose explains, describing a 1903 voyage of Lord Curzon, the British Viceroy, from Karachi to and through the Persian Gulf,

From Suez through the Arabian Peninsula to India itself, and on east to what is now Bangladesh and Burma, the British were dominant. Sea power proved decisive in this “oceanic spatial domain,” as it likewise did in China during the nineteenth century Opium Wars. Arguably the two Opium Wars show how even the Indian Ocean is not big enough to tell the story of British, let alone global, sea-borne empire. It was opium, grown in India but exported—lucratively, and by sea—to China, that led to the wars of that name and ushered in a sea change in China’s relationship with the West.

Imperial Britain had long sought greater access to the vast market of China. Yet unlike in India, the British made little headway. The infamous Macartney delegation of 1793, an ill-fated attempt to wow the Chinese with English manufactures and initiate a robust trading relationship, took over a year of travel and massive effort yet produced almost no change. The Chinese openly disdained the British. The Qianlong Emperor, in a contemporaneous letter to King George, declared: “We possess all things. I set no value on objects strange or ingenious, and have no use for your country’s manufactures.”Footnote ⁶³ Reflecting the traditionally dim Chinese view of the oceans, the Qianlong Emperor pityingly referred to “the lonely remoteness of your island, cut off from the world by intervening wastes of sea.”Footnote ⁶⁴ Yet it was precisely these “wastes of sea” that allowed the British to import the one thing, it turned out, the people of China did desire from the outside world.

British traders began smuggling ever larger quantities of opium from India as the nineteenth century began. Facing growing addiction and a worrying outflow of silver, the Qing dynasty eventually ordered the traders out. Sent to protect British interests, the Royal Navy crossed the wastes of sea in response. The British warships routed the Chinese forces handily. Shocked at the overwhelming weaponry of the West, the Qing dynasty swiftly conceded. This defeat is generally taken to mark the beginning of the “century of national humiliation,” in which forces and ideas from the West increasingly dominated an enfeebled China.Footnote ⁶⁵ The humiliation was intensified in the Second Opium War, which coincided with the Taiping Rebellion, a massive civil war led by a rebel from the southern provinces improbably claiming to be the brother of Jesus Christ.

A young reporter for the New York Daily Tribune named Karl Marx observed the catastrophic impact of these events on China. Marx indirectly noted the role of the sea—which bore on its surface the warships and weapons, but also the goods, people, and even ideas of the West—as a vector for change in the political order of Asia. The English and their cannon, Marx wrote in 1853, “forced the Celestial Empire into contact with the terrestrial world”:

The consequences of China’s stunning defeat in the Opium Wars ranged widely: from further opium trade to the opening, via the Treaty of Nanjing, of new ports for commerce and the gradual erosion of Chinese control of its territory. China was never colonized as India was. But it soon became pockmarked by “concessions” to Western powers in coastal cities such as Shanghai. Perhaps most impactfully for British sea power, the Treaty of Nanjing included the acquisition of a strategic and vertiginous harbor island in the Pearl River Delta, known as Hong Kong.Footnote ⁶⁷

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Coastal islands, Colin Flint writes in Near and Far Waters, can serve as the “connective tissue of the tentacles of sea power” (Flint, p. 144). Indeed, Hong Kong proved central to the British presence in East Asia for well over a century. (It was only returned to China in 1997.) Hong Kong and its spectacular harbor became a major trading port and base for the Royal Navy, fueling what Flint dubs the “virtuous cycle of sea power”: Maritime supremacy leads to maritime trade, which garners maritime resources, which build naval strength, which yields still greater maritime supremacy (Flint, p. 18, 163). This cycle bolstered British hegemony in the nineteenth century. It did the same for the United States, when in the wake of the Spanish-American War the nation began its slow march to global pre-eminence by, as great powers at the time did, acquiring colonies in far waters.Footnote ⁶⁸ And it is being replicated today by China—though, Flint argues, this cycle is often viewed in its new twenty-first century incarnation as somehow less than virtuous.

A geographer, Flint does not say much about international law’s role in this process of sea power acquisition. (Neither, unfortunately, does Bose.) Yet it is of course central. Maritime supremacy depends on doctrinal features large and small that permit the great powers to send their navies through narrow straits, across vast oceans, and through the territorial seas of strategic islands and coasts. The law of international trade facilitates traffic in goods, encourages economic openness and integration, and builds wealth. Treaties—such as UNCLOS—guarantee access to the high seas and coastal features alike. Like many liberal features of world order, the law of the sea lays out neutral, open rules and principles. These nonetheless tend to advantage the strongest. While every state has the right of innocent passage, for instance, there are only a handful of states with the ability to project force throughout the full breadth of the oceans. (Of the forty-seven aircraft carriers currently in service worldwide, one third belong to a single nation: the United States.)Footnote ⁶⁹ For these states, as The Free Sea amply demonstrates, the freedom of navigation enshrined in the law of the sea is essential to their global power. For everyone else, it represents a means by which that power may be brought to bear upon them.

Which brings us back to the Arctic voyage of the Meishan and the Xiushan. China has an “unprecedented” footprint in the Arctic today, U.S. Northern Command Chief General Gregory Guillot argued in 2025.Footnote ⁷⁰ Whether China is truly an Arctic power or not, its maritime aspirations there and in other far waters increasingly worry many in Washington. China’s industrial capacity is massive. Its share of global commercial shipbuilding stands today at over 50 percent; the United States, once a major shipbuilding nation, is at a comparatively tiny 0.1 percent.Footnote ⁷¹ By some counts, the People’s Liberation Army Navy now is the largest in the world.Footnote ⁷² The century of national humiliation is long over; the spirit of Admiral Zheng He has returned. Beijing seems increasingly inclined to send its growing fleet wherever it chooses. A decade ago, Chinese spy ships began to appear off the coasts of Hawaii and Guam.Footnote ⁷³ Americans on the mainland may soon be alarmed by the sight of Chinese warships on the horizon, freely navigating through the near waters of California or Oregon. In the same vein China, following the path laid down by the British and the Americans, may also seek to extend its network of overseas naval bases far beyond its current footprint in the Western Pacific. (China has one acknowledged overseas base in Djibouti, officially constructed to aid anti-piracy efforts in the Horn of Africa, and one shared base in Cambodia. There are also over one hundred ports around the world that are Chinese-built and operated that many in the West view as dual-use facilities.)Footnote ⁷⁴

In 2024, the U.S. director of national intelligence’s annual assessment argued that China will continue to pursue

In response, a Chinese Embassy spokesman noted that Chinese ships sail, just as Chinese people travel and live, throughout the entire world. The United States possesses “over a hundred military bases across the world, deploying hundreds of thousands of troops beyond its homeland. It has fought one war after another outside its territory. It is not in a position to accuse other countries in this regard,” the spokesman retorted.Footnote ⁷⁶

While many American officials have claimed that China is undermining the rules-based order that Washington—until recently—often championed, Beijing is in fact generally supportive of the international legal order as it sees it.Footnote ⁷⁷ But the law of the sea may be an important exception. China certainly has the right to establish naval bases and to sail anywhere it chooses consistent with the law of the sea. Yet its actions in the South China Sea, resting on dubious legal claims, have aroused substantial criticism and concern.

China claims a very large portion of the South China Sea for itself, arguing it has “indisputable sovereignty … and jurisdiction over … [its] islands … and the adjacent waters … as well as the seabed and subsoil thereof ….”Footnote ⁷⁸ Beijing’s infamous Nine-Dash Line extends like a huge tongue down from Taiwan and Hainan Island to skirt the shores of the Philippines all the way to the distant coasts of Borneo and Southern Vietnam. It covers approximately two million square kilometers, an area five times the size of California.Footnote ⁷⁹ Chinese vessels have repeatedly challenged the vessels of other nations in this large area in threatening ways.Footnote ⁸⁰ And China has dredged massive amounts of sand to build up artificial islands on reefs and atolls, some of which are sizeable enough to include airstrips, deep water ports, and military bases. This has created some 3,200 acres of new land surface, nearly all of it disputed by various neighboring coastal states.Footnote ⁸¹

The core of China’s claim is that it enjoys “historic rights” over this maritime expanse, and that these rights have been established through its “long-standing historical presence and display of authority.”Footnote ⁸² Beijing first made this claim in 1958. It reiterated it in various forms over the ensuing decades, including its ratification of UNCLOS in 1996. Yet it never did so with much clarity or offered any serious legal analysis in support. UNCLOS does not employ the term historic rights. “Historic bays” appear in Article 10; Article 15 provides that the general rule governing delimitation of overlapping territorial seas does not apply in instances of “historic title or other special circumstances.”Footnote ⁸³ These are certainly analogous concepts to historic rights, but only roughly. The U.S. view is that these provisions are “strictly limited,” applying only to bays and “similar near-shore coastal configurations” and therefore not EEZs, continental shelves, or the high seas.Footnote ⁸⁴

China’s Nine-Dash Line map (at one point, eleven-dashes long, and perhaps now comprising ten)Footnote ⁸⁵ is often wielded in tandem with these claims. In Burkina Faso v. Mali (1986), the International Court of Justice held that maps, however, are merely informative.Footnote ⁸⁶ They cannot establish a claim to sovereignty over a frontier. A map may, in some circumstances, serve as probative evidence of a larger territorial claim.Footnote ⁸⁷ But as Florian Dupuy and Pierre-Marie Dupuy argue, despite its ubiquity the Nine-Dash Line map lacks even that weight:

In 2013, an arbitral tribunal, sitting at the Permanent Court of Arbitration in the Hague, heard claims brought by the Philippines against China concerning the South China Sea. The proceedings, which stretched on for three years, featured a who’s-who of international lawyers on the side of the Philippines; Beijing refused to participate, issuing a note verbale at the onset stating that it “does not accept the arbitration initiated by the Philippines.”Footnote ⁸⁹ (Interestingly, China broke with much of the developing world during UNCLOS over the desire to include compulsory dispute settlement, arguing that it was contrary to the principle of state sovereignty.)Footnote ⁹⁰

The arbitral ruling, some 500 pages long, was cleverly organized around the legal status of maritime features rather than the adjudication of who controlled what feature. It offered an extensive, detailed analysis of UNCLOS’ “regime of islands.”Footnote ⁹¹ In the process, the arbitrators decided that the maritime features in question, such as the Spratlys, were not, in fact, islands. They instead were low-tide elevations or rocks. Importantly, neither category generates an EEZ. And only islands and rocks, which as a legal matter are essentially unhabitable islands, can generate a territorial sea—inside of which, for example, submarines must surface.Footnote ⁹² The result was a decisive victory for the Philippines and a substantial blow to the legitimacy of Chinese maritime claims.

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In The Free Sea, Kraska and Pedrozo argue that China’s “expansive and unlawful” claims in the South China Sea are largely driven by geography (Kraska & Pedrozo, p. 247). China is a vast continental state. Yet it is hemmed in by the so-called First Island Chain—stretching from Russia down through Japan, Taiwan, and the Philippines—and seeks greater access to the open ocean. The South China Sea ruling, they suggest, is a major barrier to Beijing’s pursuit of supremacy in the Western Pacific. China still may attempt to claim various features as islands and may even patrol them or turn them into artificial islands. But the lawfulness of doing so has now been deeply undermined. Great powers often do what they want, at times flouting international law in the process. (The recent U.S. decision to permit seabed mining is a good example.) Whether—as NOAA astutely noted in 2017—other states recognize such unlawful acts is, of course, a separate question.

Disputes over the South China Sea are not limited to China. The complex geography of the region engenders overlapping legal claims, and many Southeast Asian littoral states have a long history of feuding amongst themselves. Urbina, in The Outlaw Ocean, recounts a standoff between an Indonesian ship patrolling for illegal fishing boats and the Vietnamese Coast Guard. As guns fixed on his vessel, both sides adamantly debated whether they were in Indonesian or Vietnamese waters (Urbina, p. 308).Footnote ⁹³ Even if China were to suddenly withdraw its expansive legal claims, these arguments between Southeast Asian states over maritime entitlements would persist.

In the years since the Philippines arbitration tensions have continued at full throttle. Chinese ships, whether coast guard or so-called maritime militia,Footnote ⁹⁴ often harass foreign vessels. In May of 2025, for instance, Manila released a video of a Chinese coast guard vessel dangerously cutting off a Philippines fisheries bureau ship and firing a water cannon across its bow.Footnote ⁹⁵ These encounters are especially fraught because since 1951, the United States and the Philippines have had a mutual defense treaty. Recently, the United States reiterated that an armed attack in the Pacific, “including anywhere in the South China Sea,” would be sufficient to trigger the mutual defense commitments of the treaty.Footnote ⁹⁶ These clashes between China and the Philippines are a worrisome development—especially as the United States and China appear increasingly at odds over trade, technology, and Taiwan.

Some understandably interpret these developments as a fundamental threat to the law of the sea. China is “challenging the West in our dominance of the rules,” one NATO official recently asserted, while “proactively using them” to their own advantage.Footnote ⁹⁷ But as Beijing likes to stress, it is China that is a party to UNCLOS and the United States that is not. (A Foreign Ministry spokesman in 2024 noted that the United States “selfishly refuses to accede to UNCLOS, and yet often lectures other countries on their implementation of UNCLOS.”)Footnote ⁹⁸ China’s rhetoric in this regard is of a piece with its general critique of the so-called rules-based order, which Beijing has long seen as selective and amorphous “house rules” of the West.Footnote ⁹⁹ Still, as a superpower with global reach China, like the United States, has much to gain from a stable and broadly accepted legal maritime order.

In 1954, in the early years of the People’s Republic, China put forward the “Five Principles of Peaceful Coexistence.” These are mutual respect for sovereignty and territorial integrity; mutual non-aggression; mutual non-interference in each other’s internal affairs; equality and mutual benefit; and peaceful coexistence.Footnote ¹⁰⁰ At the seventieth anniversary celebration of these principles in 2024, Beijing issued a declaration noting that these principles, “informed by Asian wisdom,” and consistent with the purposes and principles of the UN Charter, have become “open, inclusive, and universally applicable basic norms for international relations and fundamental principles of international law.”Footnote ¹⁰¹

Developed over centuries, the law of the sea is arguably an exemplar of these principles. It has long allowed states to share and allocate the bounty of the ocean while pursuing their national interests peacefully. Negotiated as the sea’s seemingly limitless capacity began to be questioned for the first time, UNCLOS encapsulated the accretion and extension of these often-ancient rules even as the participants jockeyed to protect their parochial interests. The law of the sea’s most fundamental feature, however—that it is, in Grotius’s words, a Mare Liberum—is also what has made it so central to the projection of force and influence by some states against others. As The Free Sea, Near and Far Waters, and A Hundred Horizons all demonstrate, albeit in very different ways, the oceans are the world’s most potent vector of power.

Still, even as the law of the sea enables the projection of force, it tempers it. And in UNCLOS’ careful attention to the distribution of the economic bounty of the oceans, it ever so slowly serves to recalibrate the material underpinnings of national power. All this is to say the law of the sea reflects the larger body of public international law: frequently caught between apology and utopia, yet also creating substantial friction for the naked exercise of force—and legitimating and strengthening the claims of those who appeal to doctrine over dictates. As China knows only too well, the oceans have long served as a major carrier of change. They “connect everyone with everything.”Footnote ¹⁰² As conflict rises on their surface—and even below it—adherence to the fundamental principles of international law that UNCLOS painstakingly codified ultimately offers the most promising pathway to a world of more peaceful coexistence.