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Understanding the Limits: How Far Off the US Coast is International Waters?

In the simplest terms, international waters, also known as the high seas, are areas of the ocean that are not under the jurisdiction of any country. These waters allow for freedom of navigation, fishing, and other activities that are not subject to the laws and regulations of a specific nation. But how far off the US coast is international waters? In general, international waters begin 12 nautical miles (22.2 kilometers) away from a country’s coastline.

The Territorial Sea and Exclusive Economic Zone

Before diving deeper into the topic, it’s essential to understand the two main maritime zones that extend from a country’s coast: the territorial sea and the exclusive economic zone (EEZ).

The Territorial Sea

The territorial sea is a belt of water that stretches 12 nautical miles from the baseline of a coastal state. In this area, the coastal state has full sovereignty, subject to certain rights and duties recognized under international law. The coastal state can enforce its laws, regulate usage, and exploit resources within this zone. It’s important to note that this limit is measured from the baseline rather than the actual coastline, which is usually the low-water line along the coast.

The Exclusive Economic Zone (EEZ)

Beyond the territorial sea lies the EEZ, extending 200 nautical miles (370.4 kilometers) from the baseline. Within this zone, the coastal state has special rights to explore, exploit, conserve, and manage natural resources, both living and non-living. While the coastal state has jurisdiction over resources, it cannot control the freedom of navigation and overflight or other internationally lawful uses of the sea.

International Waters and the United States

For the United States, the 12-nautical-mile limit for territorial waters and the 200-nautical-mile limit for the EEZ are applicable to all coasts, including the Atlantic, Pacific, Gulf of Mexico, and the Arctic Ocean. However, in areas where the distance between two countries’ coastlines is less than 400 nautical miles, such as the Gulf of Mexico or some parts of the Atlantic, the EEZ limits may be determined by agreements between the relevant coastal states.

Implications and Challenges in International Waters

As mentioned earlier, the high seas are open to all nations, and no state can claim sovereignty over them. This freedom allows for navigation, overflight, laying submarine cables and pipelines, and other internationally lawful uses. However, this freedom also comes with challenges and potential conflicts.

Environmental Concerns

One significant challenge is the protection of the marine environment and its resources. In international waters, overfishing and pollution can lead to the depletion and degradation of valuable ecosystems. According to Dr. Sylvia Earle, a renowned marine biologist and oceanographer, The high seas are the least protected part of the global ocean, and that’s a problem because they make up nearly half of the planet’s surface.

Maritime Security and Disputes

Another challenge is maritime security and the potential for disputes between nations. While freedom of navigation is a cornerstone of international maritime law, countries may have differing interpretations of their rights and obligations, leading to tensions and conflicts.

For example, in the South China Sea, disputes over territorial claims and access to resources have led to increased military presence and diplomatic tensions between several countries, including the United States, China, and various Southeast Asian nations. In such cases, international law and diplomacy play crucial roles in resolving disagreements and maintaining peace and stability.

The Role of International Law

The United Nations Convention on the Law of the Sea (UNCLOS) is the primary international treaty governing the use and conservation of the world’s oceans. It establishes the legal framework for maritime zones, including the territorial sea, the EEZ, and the high seas. The United States, while not a party to UNCLOS, follows many of its provisions as customary international law.

Regulating Activities in International Waters

Various international organizations and treaties help regulate activities in international waters to address environmental and security concerns. Some of these organizations and agreements include:

  • International Maritime Organization (IMO) – A specialized agency of the United Nations responsible for the safety, security, and environmental performance of international shipping.
  • International Seabed Authority (ISA) – Established under UNCLOS, the ISA is responsible for organizing and controlling activities related to deep-sea mining in international waters.
  • Regional Fisheries Management Organizations (RFMOs) – These organizations manage and conserve fish stocks in specific areas of the high seas, promoting sustainable fishing practices.
  • United Nations Fish Stocks Agreement (UNFSA) – This agreement aims to ensure the long-term conservation and sustainable use of straddling and highly migratory fish stocks.


International waters, starting 12 nautical miles off the US coast, provide an essential space for freedom of navigation, trade, and communication. However, this freedom also presents challenges, such as environmental degradation and maritime disputes. International law, treaties, and organizations play a vital role in addressing these issues and ensuring the sustainable use and conservation of the world’s oceans. As our understanding of the oceans’ importance continues to grow, so too must our commitment to responsible stewardship and international cooperation.

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