The United Nations Convention on the Law of the Sea (UNCLOS) divides the world’s oceans into a series of legally distinct maritime zones, which each confer different rights and obligations on the coastal states they belong to and other users of the sea.
These zones attempt to balance two competing principles: mare clausum (directly translated as “the closed sea”, this refers to the extension of coastal state jurisdiction) and mare liberum (directly translated as “the free sea”, this refers to the preservation of the oceans as a shared domain for navigation, commerce, and security). These principles – and conflicting views how they should be interpreted and applied – have been a major and persistent source of geopolitical tensions.
Diagram of maritime zones under international law by the National Oceanic and Atmospheric Administration
In this article we will cover each of these maritime zones, beginning with internal waters and extending seaward out to the high seas, outlining their legal status, scope, and key areas of controversy.
