The
United Kingdom, at least, has
extended this limit to ten miles. This caused some friction with the
Principality of Sealand at the time, which became enveloped by the limit.
Sealand retaliated by extending its own
sovereign territory out to 10 nautical miles.
BTW, the UK originally set the limit at 3 miles because that was the longest distance from which a cannonball could penetrate one foot of Oak.