In August of 1937, Gilbert Manter reported seeing a sea monster 120 feet long in the waters off of Nantucket, Massachusetts. There was a subsequent sighting and footprints were even discovered on the beach.
Eventually, the monster showed itself and was even photographed!
As it turns out though, the sightings and footprints had been part of a hoax --more like a practical joke or publicity stunt-- orchestrated by Tony Sarg and some other local residents. Tony Sarg was a children's book illustrator who also designed animated window displays for Macy's Department Store in New York. He also created the first hot air balloons for Macy's Thanksgiving Day Parade -- a skill that came in handy when he orchestrated the sea serpent hoax.
The hoax didn't last long though. The "monster" was eventually inflated on Coatue and could be seen from the harbor, and the following day it was inflated on the South Shore where it was visited by many residents.
It seems this hoax was just all in good fun.
See video footage of the event below. See more photos here.