Page "Territorial waters" Paragraph 1

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 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 ( both military and civilian ) are allowed innocent passage through it ; this sovereignty also extends to the airspace over and seabed below.