There were many sightings of the creature in 1817 in Gloucester Harbor, in Massachusetts. Nick Redfern has a new Mysterious Universe article about this cryptid, "Profiling the Gloucester Sea Serpent."
|The Gloucester Sea Serpent|
It starts out like this:
"Sightings of so-called Sea Serpents abound within the domain of monster hunting. More often than not, they are encounters of a fleeting, one-time nature. But not always. One of the most enduring of all such leviathans of the deep is that which haunts the port of Gloucester, Massachusetts, and which is situated just north of the city of Boston.
"So far as can be determined, the earliest report of the Gloucester Sea Serpent dates from 1638. The witness was a man named John Josselyn, who said: 'They took me of a sea serpent, or snake, that lay quoiled [sic] up like a cable upon the rock at Cape Ann; a boat passing by with English on board, and two Indians, they would have shot the serpent, but the Indians dissuaded them, saying that if he were killed outright, they would all be in danger of their lives.'"
You can check out the rest of Redfern's article on the serpent here.