From the Daily News:
The visitors have heard the urban legend about an escape passage built between Fort Totten in Queens, to Fort Schuyler in the Bronx, where the Long Island Sound and the East River meet.
Historians, park rangers and common sense suggest it is a myth. The technology needed to build a tunnel under more than 100 feet of water, simply didn't exist at the time, they maintain.
But speculation has been stoked by tantalizing clues - including dead-ending corridors and walled-up chambers in both forts. The enduring tale prompted the History Channel to run a segment on it recently.