Did a lot of sailing in and out of NY Harbor back in the '60s - came across a 'floater' coming back from a race. A radio call to the Coast Guard asked us for our description, and asked us to stay by it and not touch it. A crew arrived promptly and did their thing to scoop up the body. In response to our questions, they advised us that they recovered about 400 bodies a year from the harbor, and the strangest thing they'd recovered was a dead giraffe. We figured the giraffe either died in transit and was dumped off a ship, or just came down river from a zoo to the North (you need a big hole to bury a giraffe).
I wouldn't want to swim in that water, or eat a fish caught there.