Proceedings of the 14th Biennial Coastal Zone Conference - Demystifying the Maritime Zones and Other Marine Boundaries on NOAA’s Nautical Charts

Oct 13, 2026

Proceedings from the 14th Biennial Coastal Zone Conference (New Orleans, July 17-21, 2005) address how NOAA nautical charts depict complex maritime zones and marine boundaries, and how that complexity can cause public confusion. The discussion reviews the historical development of maritime-zone authority under international law, from the “cannon shot” rule to UNCLOS, and explains U.S. control in relation to foreign states’ rights. It covers territorial sea, contiguous zone, and the 200 nm EEZ, including baselines and restrictions on passage and entry.

LanguageEnglish

CategoryGeneral

FormatPDF

Pages6

Reading Time2 min

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Introduction

History of maritime zones under international law: from the cannon shot rule to UNCLOS

U.S. control in maritime zones vs rights of foreign states

Proceedings of the 14th Biennial Coastal Zone Conference New Orleans, Louisiana July 17 to 21, 2005 DEMYSTIFYING THE MARITIME ZONES AND OTHER MARINE BOUNDARIES ON NOAA’S NAUTICAL CHARTS Ole Varmer, NOAA/Office of General Counsel for International Law Suzanne Bass, NOAA/Office of Assistant General Counsel for Ocean Services Meredith Westington, NOAA/NOS/Office of Coast Survey INTRODUCTION [Ole or Meredith Westington, NOAA/NOS/Office of Coast Survey] The United States, pursuant to international treaties and customary law, has established maritime zones in which various activities are controlled or restricted. The~~se~~ limits of these zones, among a host of other information, have for years been depicted on NOAA’s paper nautical charts. NOAA is responsible for depicting on its nautical charts the limits of the 12 nautical mile Territorial Sea, 24 nautical mile Contiguous Zone, and 200 nautical mile Exclusive Economic Zone (EEZ) . While valuable, the charts can only begin to give notice to the public of the complexity of the laws that rely on these marine boundaries. At times the charts have even added to public confusion. There is only so much a piece of paper can represent – but what is the NOAA chart trying to represent? And will technology help NOAA do a better job in the future? Ole Varmer, NOAA/Office of General Counsel for International Law HISTORY OF THE MARITIME ZONES UNDER INTERNATIONAL LAW: FROM THE CANNON SHOT RULE TO UNCLOS The birth of a nation’s authority to control its coastal waters has been traced back to the sixteenth century. In the seventeenth century, the father of international law, Grotius, recognized the existence of a nation’s jurisdiction over the coastal waters that could be effectively controlled from the land. The extent to which a nation could control its coastal waters was largely based on the reach of its cannons on the shore. Thus, the 3 nautical mile (nm) limit of the territorial sea resulted from what is often referred to as the“cannon shot” rule. In the U.S., the creation of a territorial sea and contiguous zone date back to as early as the late 1700s in response to issues of national security and law enforcement at coastal areas, including a 1793 diplomatic note sent from Thomas Jefferson and legislation passed by Congress in 1799 to allow the boarding of foreign flag vessels within 12 nm from the coast. This zone was known as “customs waters” and was later called the “Contiguous Zone.” By 1930 the proprietary rights of the coastal state over the resources of the territorial sea was well established, provided it did not interfere with a vessel’s right of innocent passage. In 1945, President Truman issued a proclamation asserting rights to explore and exploit the oil and gas resources of the continental shelf outside of the 3 nm territorial sea. In 1953, the U.S. Congress enacted legislation over the federal and state control of the continental shelf. In 1958, international conventions were concluded in Geneva on the territorial sea, contiguous zone and continental shelf. The concept of a fishery conservation zone was born in another Truman Proclamation but Congress did not enact laws regarding a 200 nm fishery conservation zone until 1976. This evolved into a zone whereby a coastal nation had exclusive control over all economic exploration and exploitation of the natural Proceedings of the 14th Biennial Coastal Zone Conference New Orleans, Louisiana July 17 to 21, 2005 resources off its coast. By 1982, the custom of asserting a 12 nm territorial sea, 24 nm contiguous zone, and 200 nm EEZ was codified in the United Nations Convention on the Law of the Sea (UNCLOS) . U.S. CONTROL IN MARITIME ZONES VS RIGHTS OF FOREIGN STATES The U.S. proclaimed a 12 nm territorial sea in 1988, a 24 nm contiguous zone in 1999, and a 200 nm EEZ in 1983, consistent with customary international law as codified in UNCLOS. This customary law is a balanced compromise between a flag state’s inte

FAQs

Why does the document discuss complexity in NOAA’s nautical charts?

It explains that while NOAA charts depict key maritime boundaries, the underlying laws are complex and have sometimes increased public confusion about what the charts represent.

How are maritime zones historically linked to international law?

The document traces coastal-water control authority from early concepts of effective control (the “cannon shot” rule) through later developments, culminating in codification practices associated with UNCLOS.

What are the main U.S. maritime zones and how do their rights differ?

The document describes a 12 nm territorial sea, a 24 nm contiguous zone, and a 200 nm EEZ, noting that the U.S. does not exercise full sovereignty in the contiguous zone or EEZ, but does have exclusive sovereign rights for exploring natural resources.

Oct 13, 2026

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