Gloucester Sea-Serpent Mystery: Solved after Two Centuries

Joe Nickell

A “wonderful sea-snake” was repeatedly seen in the area of Gloucester Bay and Nahant Bay, Massachusetts, in August 1817 and again in 1819. Although attracting “hundreds of curious spectators,” plus a large reward for “his snakeship” alive or dead, the great creature escaped any such fate (Drake 1883, 156–159). The visitations have been reported in many respectable publications—including Richard Ellis’s Monsters of the Sea (1994, 48–55, 362)—and have prompted this assessment: “Whatever this animal may or may not have been, the fact remains that it is one of the most scientifically respected encounters in the annals of cryptozoology, and remains one of the great unsolved mysteries of the sea” (Morphy 2010).

Is it possible now, after two centuries, that we might actually solve the enigma? What might such a solution look like—as it begins to come dimly into view? Will it disappoint or fascinate? Or will it simply represent legend, superstition, and eyewitness error, corrected by a detective approach and access to modern research methods?


The late, great cryptozoologist Bernard Heuvelmans (1968, 149) captures something of the developing excitement over the Gloucester monster’s sudden appearance:

On 6 August 1817 two women saw a sea-monster like a huge serpent come into the harbor of Cape Ann which lies north of Gloucester roads. Little attention was paid to their story, although it was confirmed by several fishermen, but a week later so many people known to be trustworthy claimed to have seen the animal nearby, that the whole country round was much excited. On 10 August a seaman called Amos Story saw it from the shore. It was near Ten Pound Island in the shelter of Gloucester roads. On 12 August, Solomon Allen 3rd, a shipmaster, saw it from a boat, and again during most of the following day, and for a short time on the fourteenth, when it was watched by twenty or thirty people, including the Justice of Peace of Gloucester, the Hon. Lonson Nash. On that day four armed boats were sent in pursuit of the monster, and Matthew Gaffney, a ship’s carpenter, fired at it at almost point-blank range, apparently hitting it with a musket ball in the head, but doing it no harm.

Heuvelmans concludes, “There was no doubt about it, the fabulous sea-serpent was there, large as life, in Gloucester harbour.”

A broadside that appeared on August 22—titled “A Monstrous Sea Serpent: The largest ever seen in America”—provided important information, illustrating how observations were interpreted in light of the prevailing belief that such marine creatures were serpentine.

It read (Ellis 1994, 49–50):

There was seen on Monday and Tuesday morning playing around the harbor between Eastern Point and Ten Pound Island, a SNAKE with his head and body about eight feet out of the water, his head is in perfect shape as large as the head of a horse, his body is judged to be about FORTY-FIVE to FIFTY FEET IN LENGTH. It is thought that he will girt about 3 feet round the body, and his sting is about 4 feet in length.

It was first seen by some fishermen, 10 or 12 days ago, but it was then generally believed to be a creature of the imagination. But he has since come within the harbor of Gloucester, and has been seen by hundreds of people. He is described by some persons who approached within 10 or 15 yards of him, to be 60 or 70 feet in length, round, and of the diameter of a barrel. Others state his length variously, from 50 to 100 feet. 

What Was It?

That the sea-serpent went unidentified was not for lack of effort. Naturalist Constantin Rafinesque gave it his attention and believed with others that it was “evidently a real sea snake” (Ellis 1994, 54). The New England Linnaean Society even tried to palm off a new scientific designation: Scoliophis Atlanticus (Morphy 2010). A Captain Rich threw a harpoon into the monster as it swam under his whaleboat, but the iron pulled out after fifty yards. Among modern investigators, Richard Ellis (1994, 362), upon studying the case at length, asked with some exasperation, “Shall we assume that hundreds of reputable citizens were deluded or victims of mass hysteria?” Still later, a lady writing a novel had a creative idea: maybe the creature was a “poor humpback whale, entangled with a net or rope lined with keg or cork buoys” (Fama 2012).

If we hope to do better, we should begin by questioning the dogma that the creature was a great snake. In fact, as the Boston Centinel took pains to note, it did not “wind laterally along, as serpents commonly do, but his motion is undulatory, or consisting of alternating rising and depression.” Other sources, including an affidavit by a ship’s carpenter, agreed that “his motion was vertical” (Ellis 1994, 50, 51). In other words, the movement was not sideways like that of a reptile but undulating like a cetacean (a marine mammal), and that should be one of our first clues as to the creature’s identity.

Furthermore, on the sixteenth, four men at first saw the monster—not as a single serpentine creature but instead as a school of pilot whales. But, likely influenced by the prevailing view, they then came to think these “whales” looked collectively like the humps of a sea monster (Ellis 1994, 50). This is a well-known illusion, as, for instance, multiple otters can be mistaken for a single, long, multi-humped creature (Nickell 2007).

The tendency to “see” a serpentine form, by connecting the dots (or humps), seems powerful. Several eyewitnesses to the Gloucester monster got different counts: e.g., thirteen, fifteen, twenty, and thirty-two humps, thus getting overall length estimates of 100 or 120 feet or more (Ellis 1994, 50–54; Heuvelmans 1968, 165).

But what about another “serpentine” feature mentioned briefly in the Boston broadside of 1817? Recall the statement that the great snake’s “sting” (or stinger) was “about 4 feet in length.” The term sting was once used historically to mean the wound from the stinger of a snake, as in “the sting of an asp.” (Now snakes are correctly said to bite, not sting.) Indeed, in one witness’s words, the serpent “threw his tongue [i.e., his stinger] backwards several times over his head” (qtd. in Soini 2010, 107).

This archaic reference is telling, because there is indeed a marine mammal with a long tusk-like member (in fact a canine tooth) that extends from the head to a length of about 4.9 to 10.2 feet during the up-to-fifty-year life of a male. (A small percentage of females of the species also grow a tusk, but it is smaller.) It appears that this was the four-foot “sting” or “stinger” that emanated from the Gloucester sea-serpent’s head, mistaken for a tongue, and thus helps in identifying it at last as the narwhal (or narwhale), which uniquely has this feature.

A New Identification

The narwhal is a medium-sized whale—one of two living species in the family Monodontidae (the other being the beluga whale). They range in size from about thirteen to eighteen feet. They tend to congregate in groups of five to ten or even twenty or more. Groups may consist of females and young (about six feet long) or also contain juveniles and adult males. At Gloucester, we can suspect that such a group was mistaken once for a school of pilot whales, then for a single great, multi-humped sea serpent, with eventually one male exhibiting a perceived “stinger.” (That horny feature extending from the head has earned the narwhal the nickname “unicorn of the ocean,” which is all the more apt because it is “amongst the world’s rarest whales” [“Animalia” 2019].)

Indeed, I sought more evidence of the reported stinger—aware that, despite its relatively small diameter, which could make it difficult to see, more than one individual must have possessed one. In time I came upon another—mentioned in affidavits collected by the Linnaean Society (Report 1817, 153). One witness had reported seeing an open mouth, while another described, extending from the front of the creature’s head, a long pointed “prong or spear” extending two feet or so from its jaws (Report 1817, 153; Soini 2010, 107). Also, yet another witness had seen such a feature, about twelve inches long (Soini 2010, 91). I take these instances as providing clear, corroborative evidence for the existence of the narwhal’s horn-like tusk—observed on different individuals. Because the tusk makes narwhals unique among marine animals, it represents extremely strong evidence that the “creature” was actually a group of narwhals—however confusingly perceived.

Another element corroborating the identification of narwhals is found in the fact that in August 1819, the Gloucester Sea Serpent appearing at Nahant, Massachusetts, “was stationary for four hours near the shore (qtd. in Ellis 1994, 54). This is quite consistent with narwhal behavior. Its name derives from the Old Norse nár (corpse) that refers both to its greyish, mottled coloration as well as its summertime habit of lying still (called “logging”) on the surface of the water—whether in this case as an individual or “pod” (“Narwhal” 2019; “Animalia” 2019).

Among other features consistent with a narwhal was the creature’s size—an important point because witnesses were seeing only above-water portions and failed to realize whether they had seen one or multiple individuals. Also, the coloration was typically described as “dark” above and “nearly white” on the underbelly (as far as could be seen); old narwhals eventually become almost totally white (“Animalia” 2019).

A particularly distinctive feature was the creature’s ability, described by several witnesses, “to dive straight down without twisting its body in the least” (Report 1817, 153). Heuvelmans (1968, 153) observed that this could be explained if the Gloucester monster had fins or flippers on its sides (hidden under the water) as, of course, the narwhal does, having short, rounded flippers. Also, like narwhals, the monster could swim at great speed (Report 1817, 149–155). Narwhals are “unique and amazing swimmers” and often swim belly up, being capable of sudden, fast, deep dives (“Animalia” 2019).

As we have seen, descriptions of the Gloucester serpent varied widely—not surprisingly because some saw one relatively closely, while others viewed “it” from afar. One witness, for example, watched through his spyglass at a quarter of a mile’s distance. He, like most others, saw no eyes, mane, breathing holes, fins, or other fine features. Like many others, however, he reported the creature did have its head out of the water—as the narwhal often does. Most who provided testimony insisted the animal seemed quite unaggressive (Heuvelmans 1968, 152–153), again like narwhals.


The narwhal scenario I have postulated here would seem to explain why such a perceived sea serpent appeared—but only did so rarely—in Gloucester Bay, leaving a great mystery in its wake. The prevailing conviction that sea serpents were great multi-humped creatures led eyewitnesses to mistake a “pod” of smaller narwhals—which the witnesses were unfamiliar with—for a monstrous serpent.

Gloucester would have been south of narwhals’ expected range today, which includes the Atlantic area of the Arctic Ocean. Individuals are often found in the Canadian Arctic Archipelago—the northern part of Hudson Bay, for example. Narwhals do exhibit seasonal migrations, moving closer to coasts in summer months (“Narwhal” 2019). “Narwhals usually do not stray far below the Arctic Circle,” but stragglers have been recorded around Newfoundland, Europe, and the eastern Mediterranean (Drury 2019). It would not seem far-fetched for a group to have appeared as far south as Gloucester in 1817 and 1819. I think the distinguishing feature of the monster’s “sting,” “prong,” or “spear”—unique to the narwhal—argues that that is just what happened.

Today, like many mammals, narwhals are threatened by human activity. They are among those Arctic marine animals that are most vulnerable to climate change, due to reduced sea ice coverage in their environment. What an irony that two centuries after humans gathered to watch the mysterious Gloucester Sea-Serpent (and yes, attempted to kill it) we have learned its true nature—without perhaps quite yet learning our own.



I am perpetually grateful to John and Mary Frantz, who long ago generously provided an endowment for my work, which has made many of my investigations possible. I also wish to acknowledge the efforts of CFI Libraries Director Tim Binga, who continues to obtain the often obscure sources on which successful investigations depend.



  • Animalia: Narwhal. 2019.  Available online at; accessed May 6, 2019.
  • Drake, Samuel Adams. 1883. New England Legends and Folklore. Reprinted New York: Chartwell Books, 2017.
  • Drury, Chad. 2019. Monodon monoceros narwhal. Available online at; accessed May 9, 2019.
  • Ellis, Richard. 1994. Monsters of the Sea. New York: Alfred A. Knopf.
  • Fama, Elizabeth. 2012. Debunking a Great New England Sea Serpent. Available online at; accessed May 7, 2019.
  • Heuvelmans, Bernard. 1968. In the Wake of the Sea-Serpents. Translated from the French by Richard Garnett. New York: Hill and Wang.
  • Morphy, Rob. 2010. Gloucester Sea Serpent (Massachusetts, USA). Available online at; accessed April 30, 2019.
  • Narwhal. 2019. Available online at; accessed May 2, 2019.
  • Nickell, Joe. 2007. Lake monster lookalikes. Skeptical Briefs 17(2) (June): 6–7.
  • O’Neill, J.P. 2003. The Great New England Sea Serpent. New York: Paraview Special Editions.
  • Report of a Committee of the Linnaean Society of New England. 1817. Portions cited and quoted from affidavits taken from several eyewitnesses by The Hon. Lonson Nash et al., in Heuvelmans 1968, 149–155. (See also O’Neill 2003, 43–44, 51.)
  • Soini, Wayne. 2010. Gloucester’s Sea Serpent. Charleston, SC: History Press.

Joe Nickell

Joe Nickell, Ph.D., is Senior Research Fellow of the Committee for Skeptical Inquiry (CSI) and “Investigative Files” Columnist for Skeptical Inquirer. A former stage magician, private investigator, and teacher, he is author of numerous books, including Inquest on the Shroud of Turin (1998), Pen, Ink and Evidence (2003), Unsolved History (2005) and Adventures in Paranormal Investigation (2007). He has appeared in many television documentaries and has been profiled in The New Yorker and on NBC’s Today Show. His personal website is at