---
title: "Territorial Seas — AP Human Geography Definition"
description: "Territorial seas are the 12-nautical-mile zone of full state sovereignty under UNCLOS. Learn how AP Human Geo tests it against the EEZ and contiguous zone."
canonical: "https://fiveable.me/ap-hug/key-terms/territorial-seas"
type: "key-term"
subject: "AP Human Geography"
unit: "Unit 4"
---

# Territorial Seas — AP Human Geography Definition

## Definition

Territorial seas are the ocean waters extending up to 12 nautical miles from a country's coastline, where that state holds full sovereignty under the UN Convention on the Law of the Sea (UNCLOS), treated as maritime boundaries in AP Human Geography Topic 4.5.

## What It Is

Territorial seas are the strip of ocean closest to a country's coast, reaching out a maximum of 12 nautical miles from the shoreline (the baseline). Inside that strip, the state has [sovereignty](/ap-hug/unit-4/political-processes/study-guide/9WmdRJEK49Nh0Nu95fLs "fv-autolink") almost as complete as on its land. Its laws apply, it controls the airspace above, and it can police who enters. Foreign ships do get a right of "innocent passage," meaning they can sail through peacefully, but the coastal state is in charge.

The 12-mile rule comes from the [United Nations Convention on the Law of the Sea](/ap-hug/unit-4/function-political-boundaries/study-guide/UPFD3Ofw32vGtr5XYDTk "fv-autolink") (UNCLOS), the international agreement that carves the ocean into zones with decreasing levels of state control. The territorial sea is the innermost and strongest zone. Beyond it sit the [contiguous zone](/ap-hug/key-terms/contiguous-zone "fv-autolink") (out to 24 nautical miles, limited enforcement powers) and the Exclusive Economic Zone (out to 200 nautical miles, resource rights only). Think of it as sovereignty fading with distance from shore, and the territorial sea is where it's at full strength.

## Why It Matters

This term lives in [Unit 4](/ap-hug/unit-4 "fv-autolink") (Political Patterns and Processes), Topic 4.5, The Function of Political Boundaries. It supports learning objective [AP Human Geography](/ap-hug "fv-autolink") 4.5.A, which asks you to explain how international boundaries work. The CED is explicit that boundaries aren't just lines on land. EK IMP-4.B.3 says land *and maritime* boundaries shape national identity and drive disputes over resources, and the essential knowledge points directly to UNCLOS as the framework. Territorial seas are your entry point for understanding how states extend sovereignty over water, why countries fight over islands and fishing grounds, and how international law tries to manage it. If you can't tell the UNCLOS zones apart, a guaranteed style of Unit 4 multiple-choice question will catch you.

## Connections

### [Exclusive Economic Zone (Unit 4)](/ap-hug/key-terms/exclusive-economic-zone)

The EEZ extends 200 nautical miles and gives a state rights to fish, oil, and minerals, but not full sovereignty. The territorial sea is small and total; the EEZ is huge and economic-only. AP questions love making you pick between them based on distance and what the state is claiming.

### [Contiguous Zone (Unit 4)](/ap-hug/key-terms/contiguous-zone)

This is the middle layer, from 12 to 24 nautical miles out, where a state can enforce customs, immigration, and [sanitation](/ap-hug/key-terms/sanitation "fv-autolink") laws but doesn't have full sovereignty. It exists so states can stop smugglers before they reach the territorial sea.

### [Allocational Disputes (Unit 4)](/ap-hug/key-terms/allocational-disputes)

Most maritime conflicts are [allocational disputes](/ap-hug/key-terms/allocational-disputes "fv-autolink"), fights over resources like fish stocks and seabed oil. Overlapping territorial sea and EEZ claims (the South China Sea is the classic case) show exactly what EK IMP-4.B.3 means by boundaries encouraging disputes over resources.

### Globalization and Trade Networks (Unit 7)

Territorial seas sit astride the world's shipping chokepoints, like straits where the 12-mile zones of neighboring states overlap. The innocent passage rule is what keeps global trade flowing through them, linking this political boundary concept to [Unit 7](/ap-hug/unit-7 "fv-autolink")'s economic interdependence.

## On the AP Exam

Territorial seas show up almost exclusively in multiple-choice questions, and they're usually distance-matching problems. A stem describes a claim ("full sovereignty 10 nautical miles offshore" or "the right to harvest fish 180 nautical miles from shore") and you identify the correct UNCLOS zone. The numbers to lock in are 12 nautical miles for the territorial sea, 24 for the contiguous zone, and 200 for the EEZ. Anything about resource extraction far from shore is the EEZ, not the territorial sea. You may also see questions asking what UNCLOS does or doesn't provide, or which maritime designation affects global trade routes. No released FRQ has used this term verbatim, but maritime boundaries fit neatly into FRQ prompts on boundary functions and resource disputes under Topic 4.5, so be ready to use it as an example.

## territorial seas vs Exclusive Economic Zone (EEZ)

The territorial sea (12 nautical miles) gives a state full sovereignty, meaning its laws, its airspace, its control over entry. The EEZ (200 nautical miles) gives only economic rights to resources like fish and minerals; foreign ships and planes move through freely. The quick test on an MCQ is to check the distance and the type of claim. Full control close to shore is the territorial sea. Resource rights far from shore is the EEZ.

## Key Takeaways

- Territorial seas extend up to 12 nautical miles from a country's baseline, and within them the state has full sovereignty over the water, seabed, and airspace.
- The 12-mile limit is set by UNCLOS, the UN Convention on the Law of the Sea, which the AP CED names as the framework for maritime boundaries.
- Foreign vessels retain a right of innocent passage through territorial seas, which is why global shipping can still move through coastal waters.
- Memorize the UNCLOS ladder: territorial sea to 12 nautical miles, contiguous zone to 24, and Exclusive Economic Zone to 200, with state control weakening at each step.
- Per EK IMP-4.B.3, maritime boundaries like territorial seas can spark resource disputes, with overlapping claims in places like the South China Sea as the go-to example.

## FAQs

### What are territorial seas in AP Human Geography?

Territorial seas are the ocean waters extending up to 12 nautical miles from a country's coast, where the state exercises full sovereignty under UNCLOS. The concept appears in Unit 4, Topic 4.5, on the function of political boundaries.

### How far do territorial seas extend?

Up to 12 nautical miles from the coastal baseline, the maximum allowed under the UN Convention on the Law of the Sea. That exact number is a favorite AP multiple-choice answer.

### What's the difference between territorial seas and the Exclusive Economic Zone?

The territorial sea (12 nautical miles) means full sovereignty, while the EEZ (200 nautical miles) only grants rights to economic resources like fish and seabed minerals. A claim about extracting resources 180 miles offshore is an EEZ claim, not a territorial sea claim.

### Can a country block all foreign ships from its territorial sea?

No. UNCLOS guarantees foreign vessels a right of innocent passage, meaning they can sail through peacefully without the coastal state's permission. The state can still enforce its laws against ships that aren't passing innocently.

### Is the contiguous zone the same as the territorial sea?

No. The contiguous zone runs from 12 to 24 nautical miles offshore, and there the state can only enforce specific laws like customs and immigration. It does not have the full sovereignty it holds in the territorial sea.

## Related Study Guides

- [4.5 The Function of Political Boundaries](/ap-hug/unit-4/function-political-boundaries/study-guide/UPFD3Ofw32vGtr5XYDTk)

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