Maritime boundaries are the legal limits of a state's control over the ocean next to its coast, measured outward from the shoreline baseline. Under the UN Convention on the Law of the Sea, they include a 12-nautical-mile territorial sea and a 200-nautical-mile exclusive economic zone (EEZ).
Maritime boundaries answer a question land borders can't. Where does a country's power end when the territory is water? Instead of a single line, international law draws a series of zones extending outward from a coastal state's baseline (basically its low-tide shoreline). The two zones AP Human Geography cares about most are the territorial sea, which stretches 12 nautical miles out and works almost like sovereign land, and the exclusive economic zone (EEZ), which stretches 200 nautical miles out and gives the state exclusive rights to resources like fish, oil, and natural gas, but not full sovereignty.
These zones come from the United Nations Convention on the Law of the Sea (UNCLOS), the treaty framework that standardized maritime claims. The catch is geometry. When two countries sit closer than 400 nautical miles apart, or when several states ring the same sea, their claims overlap, and that's where disputes start. The South China Sea is the textbook case, with multiple states claiming overlapping EEZs around the same islands and shipping lanes. Maritime boundaries fall under LO 4.4.A, defining the types of political boundaries geographers use, and connect to LO 4.6.A on how boundaries function internationally.
Maritime boundaries live in Unit 4 (Political Patterns and Processes), specifically Topic 4.4 (Defining Political Boundaries) and Topic 4.6 on the function of boundaries. They support LO 4.4.A, which asks you to define the boundary types geographers use, and LO 4.6.A, which asks you to explain what international boundaries actually do. Maritime boundaries are the clearest example of a boundary whose main job is economic. Drawing a line in the ocean decides who gets the fish, the oil under the seabed, and control of shipping routes. That makes this term a go-to example whenever a question asks why boundaries cause conflict or how they shape resource access. It also connects to the bigger Unit 4 theme that sovereignty isn't just about land; states project power over water, airspace, and resources too.
Keep studying AP Human Geography Unit 4
Territorial Sea (Unit 4)
The territorial sea is the innermost maritime zone, extending 12 nautical miles from the baseline. Inside it, a state has nearly full sovereignty, so think of it as the country's land borders continued into the water. It's the strictest zone in the maritime boundary system.
Exclusive Economic Zone (EEZ) (Unit 4)
The EEZ extends 200 nautical miles out and gives the coastal state exclusive rights to economic resources, fishing, drilling, and mining, while still letting foreign ships sail through freely. It's the zone most likely to spark disputes because it's huge and full of valuable stuff.
Continental Shelf (Unit 4)
States can claim seabed resources on their continental shelf even beyond the standard EEZ, which is why countries argue over where the shelf 'ends.' Arctic claims by Russia, Canada, and others hinge on exactly this kind of geological boundary argument.
Armed Conflict over Boundaries (Unit 4)
Overlapping maritime claims are a major modern source of interstate tension. The South China Sea disputes show how EEZ overlaps around small islands can pull multiple states into standoffs over fishing rights, oil, and naval access. It's the maritime version of the boundary disputes you study on land.
Maritime boundaries usually show up in multiple-choice questions through UNCLOS, the territorial sea, and the EEZ. A typical stem gives you a map of overlapping claims (the South China Sea is a favorite) and asks you to identify the zone involved or explain the source of the dispute. Know the two numbers cold, 12 nautical miles for the territorial sea and 200 for the EEZ, and know what rights each zone grants. No released FRQ has centered on this term verbatim, but FRQs on boundary disputes, sovereignty, or resource conflict reward maritime examples, especially when a prompt asks you to explain why states dispute boundaries or how boundaries affect economic activity. The skill being tested is application. Don't just define the EEZ; explain what a state can and can't do inside one.
Maritime boundaries are the whole system of ocean zones; the EEZ is just one zone within it. The bigger trap is treating the EEZ like sovereign territory. It isn't. A state owns the resources in its EEZ (fish, oil, minerals out to 200 nautical miles), but foreign ships and planes can pass through freely. Full sovereignty only applies in the territorial sea, the first 12 nautical miles. If a question hinges on 'who controls the water itself,' that's territorial sea; if it hinges on 'who gets the resources,' that's EEZ.
Maritime boundaries set the legal limits of a state's control over the ocean, measured outward from its coastal baseline.
The territorial sea extends 12 nautical miles and gives the state nearly full sovereignty, almost like land territory.
The exclusive economic zone (EEZ) extends 200 nautical miles and grants exclusive resource rights, but foreign ships can still pass through freely.
The UN Convention on the Law of the Sea (UNCLOS) is the international framework that standardized these zones.
Disputes happen where claims overlap, like the South China Sea, making maritime boundaries a strong example for any question about boundary conflicts or resource competition.
On the exam, maritime boundaries support LO 4.4.A (types of political boundaries) and LO 4.6.A (how international boundaries function).
Maritime boundaries are the legal limits of a state's jurisdiction over the ocean next to its coast. Under UNCLOS, they include a 12-nautical-mile territorial sea with near-full sovereignty and a 200-nautical-mile EEZ with exclusive resource rights.
No. A state owns the economic resources in its EEZ, like fish and offshore oil, but it does not have full sovereignty there. Foreign ships and aircraft can pass through an EEZ freely, unlike the territorial sea, where the state's control is nearly absolute.
The territorial sea extends 12 nautical miles and works like sovereign territory. The EEZ extends 200 nautical miles and only grants exclusive rights to resources. Sovereignty versus resource rights is the distinction the exam tests.
Because when states sit less than 400 nautical miles apart, their 200-mile EEZ claims overlap, and whoever wins the boundary wins the fish, oil, and gas. The South China Sea, where several states claim overlapping zones around the same islands, is the go-to AP example.
UNCLOS is the United Nations Convention on the Law of the Sea, the treaty framework that defines maritime zones like the territorial sea and EEZ. Yes, know it. It's the standard answer to how maritime boundaries get defined in Topic 4.4.