Territorial Waters Explainer
Territorial waters, more precisely called the territorial sea, are the belt of sea next to a coastal state over which it exercises sovereignty under international law. That sovereignty also extends to the airspace above and the seabed and subsoil below. A state may claim a territorial sea up to twelve nautical miles from its legally determined baselines. The distance is not simply measured from any convenient point on a beach. Baseline rules, coastal geography, and boundaries with neighboring states can affect the area involved.
The territorial sea is different from several other maritime zones. Internal waters generally lie landward of the baseline, while a contiguous zone and an exclusive economic zone involve different forms of authority farther offshore. These distinctions matter because a government’s rights are not identical throughout the ocean. Sovereignty in the territorial sea is also subject to relevant international rules, including the right of innocent passage for foreign ships. That right permits qualifying passage without treating the waters as an unrestricted extension of the high seas.
Consider a foreign merchant vessel traveling along a coast within the territorial sea. Its passage must meet the applicable requirements, including the standard that it not prejudice the coastal state’s peace, good order, or security. The coastal state can adopt certain lawful rules concerning passage, but its authority is constrained by international law. Entering a port can involve a different legal position from simply passing through the territorial sea. The location, activity, and legal regime all need to be identified before deciding what a coastal government may require.
Disputes can arise over baselines, overlapping claims, passage rights, and the interpretation of particular activities at sea. A line on a map does not alone settle whether a claim complies with international law. Nor should all offshore waters be described as a country’s territory merely because it has resource rights there. For readers following maritime debates, the questions are which zone the vessel occupies, how its boundary was determined, and what the vessel is doing. Those details clarify the balance between coastal sovereignty and the rights that international law preserves for other states.
A territorial sea may extend up to twelve nautical miles from lawful baselines. It is not measured from an arbitrary offshore point.
Coastal sovereignty extends to the territorial sea’s water, airspace, seabed, and subsoil, subject to applicable international law.
Foreign ships have a right of innocent passage under relevant conditions. Coastal sovereignty does not eliminate every passage right.
Internal waters, the contiguous zone, and the exclusive economic zone have different legal regimes. Identify the zone before assessing authority.
Port entry is distinct from passage along a coast. A vessel’s activity can change which rules apply.
Baseline disputes and overlapping claims can complicate boundaries. A national map does not by itself establish a claim’s legality.
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