<P> Territorial waters or a territorial sea, as defined by the 1982 United Nations Convention on the Law of the Sea, is a belt of coastal waters extending at most 12 nautical miles (22.2 km; 13.8 mi) from the baseline (usually the mean low - water mark) of a coastal state . The territorial sea is regarded as the sovereign territory of the state, although foreign ships (civilian) are allowed innocent passage through it, or transit passage for straits; this sovereignty also extends to the airspace over and seabed below . Adjustment of these boundaries is called, in international law, maritime delimitation . </P> <P> The term "territorial waters" is also sometimes used informally to refer to any area of water over which a state has jurisdiction, including internal waters, the contiguous zone, the exclusive economic zone and potentially the continental shelf . </P>

How many miles out is considered international waters