{{Short description|Line from which the limits of a state's territorial sea are measured;}} {{About|the nautical concept of baselines|other uses|Baseline (disambiguation)}}
A '''baseline''', as defined by the United Nations Convention on the Law of the Sea, is the line along the coast from which the outer limits of a state's territorial sea and certain other maritime zones of jurisdiction are measured, such as a state's exclusive economic zone.<ref name=":0">{{Cite web |title=Chapter 2: Maritime Zones – Law of the Sea |url=https://sites.tufts.edu/lawofthesea/chapter-two/ |access-date=2025-09-29 |website=sites.tufts.edu}}</ref>
thumb|400px|Maritime Zones under International Law
==Measurement of baseline== thumb|right|250px|Chilean Baseline, an example of straight baseline use The following methods are used to measure a baseline under the Law of the Sea Convention. In all cases, the baseline is drawn according to the state's own charts.<ref name=":0" />
===Normal baseline=== In most cases, the baseline follows the low-water line of the coastal state. There are a variety of special rules and exceptions for a range of geological features, including bays, ports, rocks, artificial structures and reefs.<ref>{{Cite web |title=Maritime Zones and Boundaries {{!}} National Oceanic and Atmospheric Administration |url=https://www.noaa.gov/maritime-zones-and-boundaries |access-date=2025-09-29 |website=www.noaa.gov |language=en}}</ref><ref name=":0" />
===Straight baselines=== The UN Convention allows for straight baselines to be drawn where deeply indented coastline and fringes of islands are closely connected to the coastline. Straight baselines must be drawn between the features and the coastline, in the general direction of the coast, and cannot be drawn across low-tide elevations. The Convention also prohibits straight baselines that would cut off another state's access to territorial sea or Exclusive Economic Zone. Since their introduction, countries including Canada and China have used straight baselines to extend their maritime borders.<ref name=":0" />
==Particular baselines== * Baselines of the Chinese territorial sea * Baselines of Indonesia * Baselines of the Philippines
==See also== * International waters
==References== {{Reflist}} * [https://www.un.org/Depts/los/convention_agreements/texts/unclos/part2.htm United Nations Convention on the Law of the Sea (UNCLOS) – Part II]
Category:Hydrography Category:Law of the sea Category:Curves