Long Island Sound's Three Corners
... a little to the west of a line between Napatree Point, R.I., and East Point, Fishers Island ... a boat can be in the waters of Connecticut, Rhode Island and New York, all at the same time.
Now that you've whacked your forehead in astonishment, I should say that I found this fact in a column by Dave Sampson in the Norwich Bulletin, in which he discusses the pros and cons (pros, mostly) of a Connecticut proposal to require licenses for salt water fishing. One of Sampson's points is that it's a done deal. Federal law requires it, and the only choice is whether to let the state control it or hand it over to the feds.