This is a cool article posted on CNN today. Some treasure hunters found 48 gold escudos. The coins were found only 100 ft from the shore in about 6 feet of water on a popular beach. That's it! From now on I bring my metal detector on all beach excusions! http://www.cnn.com/2013/07/14/us/florida-treasure-found/index.html?hpt=hp_t4
Actually, NY is one of the better places in the US where one might try detecting because of its long history of inhabitants from the various European colonial times, revolutionary era, lots of agricultural settlements and such going forward. Perhaps not coin-wise, but there exists artifacts and history of pre-European presence, too. There was a CT member sometime back who talked about his extensive detecting of sites throughout the city and state of NY. He had made many remarkable finds over the years. If the CT database is searchable for old threads, look up Kman413.
I seem to recall a thread in this forum within the last year about a CT member metal detecting in a dried creek bed in New Jersey and found some really rare colonial coin. I don't think it was a brasher doubloon, but something along those lines. Tried a thread search but couldn't locate it.