Territorial Sea: 12 nmi

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 twelve nautical miles (12 nmi) 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 are allowed innocent passage through it; this sovereignty also extends to the airspace over and seabed below.

source: NOAA Office of Coast Survey

info: http://en.wikipedia.org/wiki/Territorial_waters