Thomas Glover's Account of Virginia (1676)

Another fishing story:

As I was coming down the [Elizabeth] river in a sloop bound for the bay, it happened to prove calm, at which time we were three leagues short of the river’s mouth; the tide of the ebb being then done, the sloop-man dropped his grapline, an dhe and his boy took a little boat belonging to the sloop, in which they went ashore for water, leaving me aboard alone, in which time I took a small book out of my pocket and sat down at the stern of the vessel to read; but I had not read long before I heard a great rushing and flashing of the water, which caused me to suddenly look up, and about half a stone’s cast from me appeared a prodigious creature, much resembling a man, only somewhat larger, standing right up in the water with his head, neck, shoulders, breast, and waist, to the cubits of his arms, above water; his skin was tawny, much like that of an Indian; the figure of his head was pyramidal, and slick, without hair; his eyes large and black, and so were his eyebrows; his mouth very wide, with a broad streak on the upper lip, which turned upward at each end like mustachioes; his countenance was grim and terrible; his neck, shoulders, arms, breast, and waist were like unto the neck, arms, shoulders, breast, and waist of a man; his hands if he had any, were under water; he seemed to stand with his eyes fixed on me for some time, and afterward dived down and a little after riseth at somewhat a farther distance, and turned his head towards me again, and then immediately falleth a little under water, and swimmeth away so near the top of the water, that I could discern him throw out his arms, and gather them in as a man doth when he swimmeth. At last he shoots with his head downwards, by which means he cast his tail above the water, which exactly resembled the tail of a fish with a broad fane at the end of it.

Hypnagogia, liquor, and/or an overactive imagination,or perhaps simply the commercial motive—you decide.