A country can dredge sand from the ocean floor, pile it into a reef, build a runway on top, and declare the whole thing sovereign territory. Whether international law agrees is a question that no court has been able to fully resolve, and several governments have decided they do not much care either way.
Executive Summary
Since 2013, China has created close to 3,200 acres of artificial land in the South China Sea, converting submerged reefs and sandbars into islands complete with airstrips, radar installations, and port facilities. In 2016, an international tribunal ruled that none of these structures qualified as islands under the United Nations Convention on the Law of the Sea, and that China had no legal basis for the maritime claims attached to them. China rejected the ruling entirely and has not moved a single dredging vessel. That collision between a legally binding ruling and a state that simply refuses to acknowledge it is the defining story of artificial islands in the 21st century. It is not just about China. It is about what happens to international law when engineering moves faster than the treaties written to govern it.
Historical Background
Humans have been building into the sea for as long as they have lived near it. The ancient Phoenicians built artificial harbors along the Lebanese coast using stone breakwaters. Venice emerged from wooden platforms driven into tidal mudflats, gradually consolidating into a city that has stood for over a thousand years. Japan's Dejima, the small artificial island in Nagasaki Bay constructed in 1634, served as the sole permitted point of contact between feudal Japan and Dutch traders for over two centuries. These were not experiments. They were deliberate engineering responses to geography, trade, and politics.
The Netherlands offers the longest running case in modern history. By the 20th century, the Dutch had reclaimed so much land from the sea through their system of polders, dikes, and pumping stations that nearly a third of the country's current territory sits below sea level. The Delta Works, a system of storm surge barriers completed in 1997, added further reclaimed land while protecting existing low-lying areas. None of this generated significant legal controversy, because the Netherlands was reclaiming land within its own territorial waters and harming no neighboring state's claimed jurisdiction.
Singapore's story is similar in mechanism, different in scale. The city-state has expanded its total land area by close to 25 percent since independence through continuous coastal reclamation, most recently by constructing the Tuas mega-port on entirely reclaimed ground. Singapore's expansion strained relations with Indonesia and Malaysia, which objected to the export of sand from their territories for use in Singapore's construction. Indonesia eventually banned sand exports to Singapore in 2007. The dispute was economic and diplomatic, not about the fundamental legal status of the reclaimed land itself.
Dubai's Palm Jumeirah, completed in 2006 at a cost of around US$12 billion, changed the conversation aesthetically and commercially. Built using 100 million cubic meters of sand and rock dredged from the Arabian Gulf floor, it added 78 kilometers of coastline and about 10,000 residences to Dubai. The Palm demonstrated that artificial island construction at spectacular scale was technically feasible for commercial purposes, and that the resulting structures could function as integrated parts of a city rather than isolated outposts. It also raised environmental concerns that have followed every major reclamation project since: the dredging obliterated local coral and seagrass ecosystems that have not recovered.
What all these projects shared was construction within recognized national jurisdiction. The legal complications that now dominate discussions of artificial islands began when states started building not within their own waters, but in disputed zones, and specifically when China began converting contested reefs and low-tide elevations in the South China Sea into permanent installations between 2013 and 2016.
Key Innovations
The technical leap that made large-scale artificial island construction viable in the open sea was the trailing suction hopper dredger. These vessels, some of the largest purpose-built ships in the world, vacuum sediment from the seabed through a drag head, store it in a hull compartment called a hopper, and deposit it precisely on a target location. China invested heavily in dredging capacity after 2006, building around 200 dredging vessels to become one of the world's largest dredger manufacturers and operators. The Xin Hai Xun, launched in 2025, has a hopper capacity of 17,000 cubic meters and represents the current ceiling of this technology.
The engineering challenge is not merely moving sand. A structure built on dredged sediment in open water is inherently unstable. The sediment compresses under load, the base shifts with currents, and wave action gradually erodes the perimeter. China's construction in the Spratlys involved driving steel sheet piles around the perimeter of each feature before filling the interior, then capping the surface with concrete and constructing permanent structures on top. What began as a reef became, over a period of months, a fixed installation indistinguishable in function from dry land, with harbors, barracks, radar arrays, and in some cases runways long enough to accommodate military aircraft.
The legal significance of this engineering is enormous, and it runs in two directions simultaneously. On one hand, the construction demonstrated that a state with sufficient dredging capacity could physically transform a submerged feature or low-tide elevation into something that looked like an island in a matter of months. On the other hand, UNCLOS Article 60 explicitly states that artificial islands do not generate territorial seas, exclusive economic zones, or continental shelf entitlements. An artificial island is not a legal island, regardless of how convincingly it resembles one from the air.
The engineering of artificial islands has outpaced the law governing them. UNCLOS was written in 1982, when the idea of converting a submerged reef into a functioning military base within a year was not a realistic planning scenario. It is now.
Infrastructure
China's Spratly Islands construction produced seven artificial islands on features that were previously reefs, low-tide elevations, or entirely submerged at high tide. Fiery Cross Reef, Subi Reef, and Mischief Reef are the three largest, each hosting a runway of approximately 3,000 meters, port facilities capable of receiving large naval vessels, radar and communications infrastructure, and permanent garrison buildings. Together they represent a network of bases positioned across a sea through which annual trade is estimated at somewhere between US$3 trillion and US$5 trillion, depending on the methodology used, making it one of the most commercially critical waterways on earth.
The infrastructure logic is straightforward. A military vessel operating from a home port thousands of kilometers away has limited patrol range and endurance. A vessel operating from a base 500 kilometers closer to a contested zone can stay on station far longer, respond to incidents faster, and project force more credibly. The artificial islands function the way forward operating bases have always functioned in military planning, except that they were built in the middle of a sea claimed by six different governments, on features that no credible legal argument could classify as Chinese territory under existing international law.
For context on how the broader legal architecture works, the Field Guide to International Water Rights and Water Treaties covers how states negotiate competing claims over shared maritime and water resources, and why those negotiations so frequently produce agreements that are difficult or impossible to enforce.
Economy
The economic stakes embedded in artificial island disputes are rarely discussed in straightforward terms, but they are large. The South China Sea contains an estimated 125 billion barrels of oil and significant natural gas reserves, though the actual figures remain contested because reliable surveying is difficult in disputed waters. The fishing grounds are valuable in their own right: the sea accounts for close to 10 percent of global fish catch annually, and the communities in Vietnam, the Philippines, and Indonesia that depend on those fisheries are not abstractions. They are fishing villages where livelihoods track directly with access to the waters that China's artificial island network now controls through its coast guard and maritime militia presence.
Dubai's commercial model demonstrates what artificial islands can do when the legal context is uncontested. The Palm Jumeirah transformed a stretch of featureless coastline into prime real estate, added hotel capacity that diversified the emirate's economy away from oil dependence, and created an internationally recognized landmark. The economic logic is repeatable. Singapore's Tuas port, built on reclaimed land, is being developed as the largest automated container port in the world. These projects generate real economic returns precisely because their legal status is clear.
The inverse is also true. When legal status is contested, the economic potential of an artificial island becomes entangled with the geopolitical cost of the dispute. China's Spratly installations have produced military capacity, not commercial returns. The fishing grounds around them are now policed by Chinese coast guard vessels in ways that exclude Filipino and Vietnamese fishermen from waters their communities have used for generations. That exclusion has economic costs that fall entirely on smaller, less powerful states.
Governance
The legal framework governing artificial islands flows from UNCLOS, signed in Montego Bay in 1982 and ratified by 168 states. Article 60 grants coastal states the right to construct artificial islands within their Exclusive Economic Zone, which extends 200 nautical miles from their baseline. It also specifies that artificial islands do not possess territorial seas of their own and cannot generate EEZ or continental shelf claims.
Article 121 defines what qualifies as a natural island: a naturally formed area of land above water at high tide. A reef that is submerged at high tide and then filled with dredged sand is not, under this definition, an island. It is an artificial installation on a former reef. The distinction sounds technical. In practice, it determines whether a state can claim an extra 200 nautical miles of maritime jurisdiction from a given feature, or none at all.
The 2016 South China Sea Arbitration ruling, issued by a Permanent Court of Arbitration tribunal under UNCLOS Annex VII, tested these provisions against China's actual construction. The tribunal found that China's nine-dash line, encompassing roughly 90 percent of the South China Sea, had no legal basis under UNCLOS. None of the Spratly features qualified as natural islands capable of generating EEZ entitlements. China had violated its environmental obligations through large-scale dredging. And it had unlawfully interfered with the Philippines' EEZ rights.
China declared the ruling "null and void." The ruling exists. The enforcement mechanism does not.
Why It Succeeded
China's island-building program succeeded, in the narrow sense that its physical objectives were achieved, for three reasons. The construction was technically straightforward given China's dredging capacity, physically irreversible once complete, and strategically timed during a period when no regional state had the military capability to stop it and no international body had the enforcement power to do so.
The broader pattern of artificial island development, as a tool of national strategy rather than purely commercial development, succeeded because UNCLOS contains a structural gap that states willing to ignore its provisions can exploit. The convention defines what artificial islands cannot do legally. It does not provide a mechanism to prevent a state from building them in violation of those definitions, and it does not empower any body to remove them once built. Once a feature has been reclaimed and a runway constructed on top, the practical situation on the water has changed regardless of what any court subsequently rules.
Dubai's commercial success and Singapore's expansion succeeded for the opposite reason: they operated within clear legal boundaries, in uncontested waters, with the consent or at least the tolerance of neighboring states. The engineering and the law pointed in the same direction. The result was development without the corrosive geopolitical friction that has followed China's program.
Where It Is Breaking Down
The system is not declining so much as bifurcating under pressure. Where artificial island construction operates within clear legal frameworks, it continues to produce commercially and strategically useful results. Where it operates in defiance of those frameworks, the result has been a progressive erosion of the authority of the legal system itself.
On the water, the situation has evolved into something the 2016 ruling did not resolve and could not prevent. The Philippines rotates a resupply mission to a deliberately grounded ship at Second Thomas Shoal. China periodically intercepts it. Vietnam, Malaysia, and Indonesia maintain their own claims, backed by their own smaller-scale construction. Several legal frameworks are simultaneously asserted by different states. None has clear precedence in any given encounter. The deciding factor is which party has more vessels present and is willing to use them.
Climate change is adding a new dimension that UNCLOS did not anticipate at all. Several Pacific island states, including Kiribati and the Marshall Islands, face the possibility that their natural islands may become submerged as sea levels rise. If the land that generates their territorial sea and EEZ entitlements disappears below the high-tide mark, does their maritime jurisdiction disappear with it? Some states are constructing artificial extensions of their existing islands to maintain above-water status. Whether this preserves their legal entitlements under UNCLOS Article 121 is an open question that has not yet been adjudicated and may reach international courts within the next decade.
What Most People Miss
Most coverage of artificial islands focuses on the South China Sea because it is the most visible and consequential case. What gets missed is that the legal ambiguity UNCLOS left around artificial islands was not an oversight. It was a deliberate product of negotiation. In 1982, when UNCLOS was being finalized, states disagreed sharply about how much jurisdiction should attach to small islands and rock outcroppings. The compromise language in Article 121, which distinguishes between islands capable of sustaining human habitation and "rocks" that cannot, and which excludes artificial structures from island status entirely, was the result of competing interests being papered over rather than resolved.
That papering-over created the gap that China has now driven 3,200 acres of dredged sand through. Legal scholar Imogen Saunders, writing in a Vanderbilt law review article, identified the UNCLOS silence on the territorial status of artificial islands as the central unresolved question in the convention. The treaty tells states what artificial islands cannot generate in terms of maritime zones. It does not tell them what artificial islands actually are in terms of territory, jurisdiction, or sovereignty. That silence is not small. It is the size of a runway.
| Country |
Project |
Purpose |
Legal Status |
Dispute? |
| Netherlands |
Polder reclamation, Delta Works |
Flood defense, agriculture, urban land |
Uncontested national territory |
None |
| Singapore |
Coastal reclamation, Tuas port |
Urban expansion, port capacity |
Uncontested, within national jurisdiction |
Sand export disputes with Indonesia, Malaysia |
| UAE (Dubai) |
Palm Jumeirah, The World |
Tourism, real estate, economic diversification |
Uncontested national territorial waters |
Environmental concerns only |
| China |
Spratly Islands reclamation (7 features) |
Military bases, maritime control |
Ruled illegal by PCA 2016; China rejects ruling |
Active disputes with Philippines, Vietnam, Malaysia, Indonesia, Taiwan, Brunei |
| Kiribati, Marshall Islands |
Shoreline reinforcement |
Preservation of above-water status due to sea-level rise |
Unresolved under UNCLOS Article 121 |
No dispute, but legal status deeply uncertain |
Timeline: Artificial Islands and Maritime Law
- 1634 — Japan builds Dejima, an artificial island in Nagasaki Bay, as the sole legal point of contact with Dutch traders.
- 1920s–1997 — Netherlands completes the Delta Works, reclaiming land that now constitutes close to a third of the country's territory.
- 1982 — UNCLOS adopted at Montego Bay. Articles 60 and 121 define the legal status of artificial islands and exclude them from generating maritime zone entitlements.
- 2006 — Palm Jumeirah completed in Dubai at a cost of around US$12 billion. China begins a major expansion of its dredging fleet, eventually building close to 200 vessels.
- 2007 — Indonesia bans sand exports to Singapore following disputes over coastal reclamation impacts.
- 2013 — Large-scale Chinese reclamation begins in the Spratly Islands. Reefs and low-tide elevations begin converting into fixed installations.
- 2016 — PCA tribunal rules China's nine-dash line has no legal basis under UNCLOS and that China violated the Philippines' EEZ rights. China declares the ruling null and void.
- 2021–present — Recurring confrontations at Second Thomas Shoal between Philippine resupply missions and Chinese coast guard vessels.
- 2025 — China launches Xin Hai Xun, the world's largest dual-fuel dredger, with a 17,000 cubic meter hopper capacity.
- 2026 — South China Sea dispute remains unresolved a decade after the ruling. Pacific island states facing sea-level rise begin testing legal options for preserving maritime jurisdiction over potentially submerged territories.
The second underappreciated dimension is what China's program triggered among other claimant states. Vietnam, Malaysia, and the Philippines have all undertaken their own smaller reclamation projects on features they occupy in the Spratlys. They are not doing so because they believe reclamation generates legal entitlements under UNCLOS. They are doing so because a fixed installation is more durable than a legal claim on paper. Every claimant state has now drawn the same conclusion and is acting accordingly.
The nuclear dimension of South China Sea tensions connects directly to this dynamic. For a deeper look at how great-power competition and international legal frameworks interact when enforcement is impossible, the Student Explainer on Nuclear Fission, Weapons, and Deterrence covers the parallel story of how legal regimes like the Non-Proliferation Treaty hold, strain, and sometimes fail when a state decides the strategic benefits of non-compliance outweigh the reputational costs.
Lessons for Modern Society
The artificial island story carries several lessons that extend beyond maritime law.
The first is about the relationship between engineering and legal frameworks. International law is written at a moment in time, by people working with the technology and scenarios that exist at that moment. UNCLOS was finalized in 1982. The dredging vessels that converted Fiery Cross Reef from a partially submerged coral formation into a 270-hectare military base did not exist at that level of capability in 1982. Every technology treaty faces the same problem: the technology eventually outruns the rules written to govern it. The question is not whether gaps will appear but how quickly and how consequentially.
The second lesson is about what happens when legal bindingness and practical effect separate. The South China Sea case has produced a decade-long demonstration that a state willing to absorb reputational costs can reshape facts on the water in ways that outlast any ruling. That lesson is not confined to maritime law. Every international legal regime, from nuclear non-proliferation to climate commitments, depends on the implicit assumption that states have some meaningful incentive to comply. When a major power shows that non-compliance carries no sufficient practical price, other states update their calculations accordingly.
The third lesson is about the climate-driven future of artificial island law. The Pacific islands facing submersion are not strategic actors pursuing territorial expansion. They are small states trying to preserve the legal basis for their own existence as sovereign entities. Their situation will force the international community to answer questions that UNCLOS deliberately avoided: can a state maintain its maritime zones if its natural land disappears? Can a state preserve its sovereignty by building artificial extensions of its sinking territory? These are not hypothetical questions for 2050. Kiribati's government has already purchased land in Fiji as a contingency. The legal architecture for what comes next does not yet exist.
Editorial View · Santhosh Vishwamitra
What strikes me most about artificial islands is how cleanly they expose the gap between what international law says and what powerful states do when the two conflict. The 2016 ruling was not ambiguous. The tribunal's language was clear. China's nine-dash line had no legal basis. The Spratly features did not qualify as islands. The construction violated environmental obligations. And China looked at that ruling and kept building.
The tribunal concluded China acted contrary to UNCLOS at nearly every point the Philippines contested. Ten years on, the more revealing question is what the international community learned from its response to that finding. What it learned, I think, is that a state willing to absorb reputational costs can reshape physical facts on the water in ways that outlast any legal ruling. The runway at Fiery Cross Reef is not going to be dismantled because a tribunal in The Hague said it should not exist. That lesson is being studied by every government that has a territorial dispute it would like to resolve in its own favor.
The climate dimension makes this more urgent, not less. When the first inhabited Pacific island drops below the permanent high-tide line, the question of what international law does for the people who lived there will not be answered by pointing to UNCLOS Article 121. That article was written for a world where islands did not disappear. We are building a world where they do. The legal architecture needs to keep up, and right now it is not even close.
Key Takeaways
- UNCLOS Article 60 permits coastal states to build artificial islands in their EEZ but explicitly states that these structures do not generate territorial seas, EEZ claims, or continental shelf entitlements of their own.
- China built approximately 3,200 acres of artificial land on seven Spratly features between 2013 and 2016, converting reefs and low-tide elevations into military installations with runways, harbors, and radar arrays.
- The 2016 PCA ruling found China's nine-dash line legally invalid, ruled none of the Spratly features qualified as natural islands, and found China had caused severe environmental harm through dredging. China rejected the ruling entirely.
- A decade after the ruling, China continues to include the nine-dash line on official maps and uses coast guard vessels and floating barriers to restrict access by Filipino fishermen to Philippine EEZ waters.
- The Netherlands reclaimed land equivalent to roughly a third of its current territory through polders and the Delta Works system, operating within uncontested national jurisdiction with no legal controversy.
- Dubai's Palm Jumeirah, built at a cost of around US$12 billion, added 78 kilometers of coastline and demonstrated commercial artificial island construction at spectacular scale, but also permanently destroyed local coral and seagrass ecosystems.
- UNCLOS does not address what happens to a state's maritime zones if its natural islands are submerged by rising sea levels, leaving Pacific island nations like Kiribati and the Marshall Islands in a legal grey zone with no established resolution.
- Vietnam, Malaysia, and the Philippines have all undertaken their own smaller reclamation projects in the Spratlys, reflecting a conclusion shared across claimant states that physical presence matters more than legal position when enforcement is impossible.
- Legal scholar Imogen Saunders identified UNCLOS's silence on the territorial status of artificial islands as a central unresolved gap in the convention, one that states with sufficient dredging capacity can exploit.
Santhosh Vishwamitra
Web Developer and Founder of Vishwamitra Chronicles, launched in February 2026.
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