AP Syllabus focus:
‘The United Nations Convention on the Law of the Sea defines rights and responsibilities in international waters, including territorial seas and exclusive economic zones.’
Understanding UNCLOS is essential for explaining how states manage maritime space. These internationally agreed rules determine ocean rights, resource access, and authority, shaping global political relationships and territorial claims.
UNCLOS as the Foundation of Maritime Governance
The United Nations Convention on the Law of the Sea (UNCLOS) structures how states define, use, and control maritime spaces. Created in 1982 and now accepted by most of the world, UNCLOS establishes a legal framework balancing state sovereignty with shared global ocean access. It differentiates maritime zones according to their distance from a state’s coastline and allocates varying degrees of sovereign rights, administrative power, and economic control. These zones shape navigation rules, fishing access, seabed mining rights, and disputes over maritime borders.
UNCLOS (United Nations Convention on the Law of the Sea): The primary international treaty that defines maritime zones and establishes states’ rights and responsibilities in marine spaces.
The convention matters to political geography because it influences boundary-making at sea, resource competition, and the strategic behavior of coastal states. Maritime zones operate similarly to land-based political boundaries: they limit authority, define jurisdiction, and help manage interactions between neighboring countries.
Coastal Baselines and the Structure of Maritime Zones
The Baseline
UNCLOS uses a baseline—usually the low-tide line along a coast—as the reference point for measuring all maritime zones. From this baseline, a series of legally defined spaces extend outward, each with different political implications.
Maritime zones under international law measured from a coastal baseline. The diagram illustrates internal waters, the territorial sea (12 nautical miles), the contiguous zone (24 nautical miles), the EEZ (200 nautical miles), and the high seas beyond national jurisdiction. Some included continental shelf labels exceed AP scope but visually clarify geological and legal distinctions. Source.
Baseline: The coastal low-water line from which maritime boundaries and zones defined by UNCLOS are measured.
These measurements allow states to claim waters in consistent ways, reducing ambiguity in where sovereignty begins and ends.
Key Maritime Zones Under UNCLOS
Territorial Sea
The territorial sea extends up to 12 nautical miles from a state’s baseline. In this space, a country exercises full sovereignty, similar to sovereignty on land, including control over people, resources, and activities. However, UNCLOS requires coastal states to permit innocent passage, allowing foreign vessels to transit so long as they do not threaten security or violate laws.
Contiguous Zone
Beyond the territorial sea, the contiguous zone extends up to 24 nautical miles from the baseline. While full sovereignty does not apply, the coastal state may enforce laws related to customs, immigration, sanitation, and taxation to prevent or punish violations originating within its territory or territorial sea.
Exclusive Economic Zone (EEZ)
The Exclusive Economic Zone (EEZ)—one of the most geopolitically significant spaces—extends 200 nautical miles from the baseline. Here, states possess sovereign rights to explore, manage, and exploit natural resources in the water, seabed, and subsoil.
Exclusive Economic Zone (EEZ): A maritime zone granting a coastal state exclusive rights to exploit marine resources up to 200 nautical miles from its baseline.
This zone affects fishing rights, offshore energy production, and maritime security strategies. It is often the source of international disputes, especially when EEZ claims overlap between neighboring countries.
Normal navigation by foreign ships and aircraft remains permitted in an EEZ, but resource decisions rest with the coastal state.
High Seas and International Waters
Beyond all EEZs lie the high seas, an open-access global commons managed collectively by the international community.
World map displaying global Exclusive Economic Zones (EEZs) as defined by UNCLOS. Shaded areas highlight coastal states’ EEZs, while unshaded ocean regions represent high seas beyond national jurisdiction. Boundary distinctions and disputed areas appear in the legend, slightly exceeding AP scope but reinforcing how overlapping claims create geopolitical tensions. Source.
No state may claim sovereignty over the high seas, though all retain certain freedoms—navigation, overflight, fishing, and scientific research. UNCLOS also prohibits activities that would harm marine environments or infringe upon shared rights.
Maritime Boundaries, Overlaps, and Disputes
Boundary Delimitation
When states are located close enough that their territorial seas or EEZs intersect, UNCLOS requires negotiation toward an equitable solution, often using a median line. These maritime boundaries can become highly contested because they determine access to valuable ocean resources such as fisheries, hydrocarbons, and minerals.
Sources of Conflict
Conflicts frequently arise when:
States disagree on how to interpret coastlines, baselines, or island status.
Energy resources lie near or across boundary lines.
Competing EEZ claims overlap.
Strategic positions such as straits or chokepoints give one state leverage over others.
UNCLOS provides mechanisms for arbitration, although compliance varies by state and geopolitical interests.
Rights and Responsibilities in UNCLOS Zones
Coastal State Responsibilities
Coastal states must:
Protect marine environments within their maritime zones.
Allow innocent passage through territorial seas.
Avoid actions that threaten shared ocean systems.
Cooperate with neighbors when zones overlap.
International Community Responsibilities
The broader international community must:
Respect the EEZ rights of coastal states.
Uphold freedom of navigation in the high seas.
Avoid overfishing and pollution.
Follow international maritime safety guidelines.
UNCLOS and Global Political Geography
UNCLOS shapes geopolitical relationships by determining who controls ocean spaces and resources. Its maritime zones influence:
Resource security, especially for states dependent on offshore oil, gas, or fisheries.
Strategic military access, including naval routes and choke points.
Boundary-making, similar to land borders but often more complex due to fluid geography.
Diplomacy and conflict resolution, as states negotiate competing claims.
By defining rights and responsibilities across maritime spaces, UNCLOS provides the legal structure through which modern states engage with the world’s oceans and negotiate their maritime boundaries.
FAQ
Sovereignty applies only to territorial seas, meaning the state exercises full authority over the water, seabed and airspace.
Sovereign rights apply in the EEZ and continental shelf, where the state controls resource use but must permit most forms of international navigation and overflight.
This distinction allows coastal states to benefit economically from offshore resources without restricting global freedom of movement.
Islands can generate territorial seas, contiguous zones and full EEZs if they can sustain human habitation or economic life.
Rocks that cannot support habitation or economic activity may generate only a territorial sea.
Low-tide elevations, which are submerged at high tide, generate no maritime zones unless they lie within a territorial sea.
These distinctions often influence major boundary negotiations and disputes.
Landlocked states have interests in maritime trade, global navigation rights and seabed resource governance.
UNCLOS includes provisions supporting landlocked states, such as rights of access to and from the sea through transit states.
Participation ensures these countries can influence decisions about global commons, environmental protection and the management of high seas resources.
Coastal states must take measures to prevent marine pollution, regulate dumping and protect endangered species within territorial seas, contiguous zones and EEZs.
UNCLOS also requires states to cooperate on shared environmental issues, such as transboundary pollution or overfishing.
International bodies can assist with monitoring, scientific research and enforcement to maintain sustainable ocean use.
UNCLOS allows states to use several legal pathways, including:
The International Tribunal for the Law of the Sea
The International Court of Justice
Arbitration or special commissions
States may choose mechanisms voluntarily, though some processes apply automatically if no agreement is reached.
These mechanisms aim to promote peaceful resolution but depend on state cooperation and compliance.
Practice Questions
Question 1 (1–3 marks)
Using your knowledge of UNCLOS, explain what is meant by an Exclusive Economic Zone (EEZ) and state its maximum distance from a state’s coastal baseline.
Mark scheme (3 marks total)
1 mark for identifying that an EEZ is a maritime zone in which a state has special or exclusive rights to exploit marine resources.
1 mark for noting that these rights include activities such as fishing or offshore energy extraction.
1 mark for correctly stating the maximum distance of 200 nautical miles from the baseline.
Question 2 (4–6 marks)
Assess how UNCLOS contributes to both cooperation and conflict between coastal states in relation to maritime boundaries.
Mark scheme (6 marks total)
Up to 2 marks for explaining how UNCLOS provides a clear legal framework for defining maritime zones (e.g., territorial seas, EEZs).
Up to 2 marks for describing how this framework can encourage cooperation, such as through negotiated boundaries or resource-sharing agreements.
Up to 2 marks for explaining how UNCLOS can also generate or expose conflict, for example when EEZ claims overlap or when states dispute baselines or island status.
