There were German subs operating all along the East coast during WW2. I believe a lot of shipping used the intracostal waterway to avoid sub attacks:http://en.wikipedia.org/wiki/American_Theater_(1939%E2%80%931945)#East_Coast Abusive comment hidden. (Show it anyway.)
http://en.wikipedia.org/wiki/American_Theater_(1939%E2%80%931945)#East_Coast