FIELD FILE · CASSIELAKE & SEA MONSTERREGIONAL LEGEND

Cassie

Also known as Casco Bay Sea Serpent, Great Sea Serpent of Casco Bay, Portland sea serpent

Casco Bay, off Portland and Cape Elizabeth, MaineFIRST REPORTED: 1779LAKE & SEA MONSTERS

Maine’s great sea serpent: a long, snakelike animal reported in and around Casco Bay since the 18th century, last famously seen off Cape Elizabeth in 1958.

Cassie is the affectionate modern nickname for the sea serpent said to haunt Casco Bay, the island-studded inlet that shelters Portland, South Portland and Cape Elizabeth. Witnesses over more than two centuries have described a long, dark, snakelike body, a head carried on a thick neck, and a habit of rising, looking around and sliding back under the cold Gulf of Maine water.

The legend draws on the oldest layer of American sea-serpent lore. The story most often told first comes from 1779, when a young Edward Preble – later a celebrated U.S. Navy commodore and a son of Portland – was serving on the Massachusetts ship Protector. As James Fenimore Cooper later retold it, the crew spotted a great serpent in Penobscot Bay (not Casco Bay itself), Preble was sent after it in a boat, and a shot from a swivel gun only sent the animal speeding away.

During the 19th century, Portland newspapers printed a steady trickle of reports. The Portland Argus described a creature in Portland Harbor in the summer of 1818, the same years that a famous sea serpent was being chased off Gloucester, Massachusetts. Later accounts placed serpents off Cape Elizabeth, in the Fore River and near Wood Island Light, and a Maine sea captain, Benjamin J. Willard, wrote of spending days hunting the animal without ever laying eyes on it himself.

The most cited modern sighting came in June 1958, when fisherman Ole Mikkelsen and his mate were working about five miles off Cape Elizabeth near the Portland lightship. Mikkelsen later said the animal looked well over 100 feet long, light brown, with a mackerel-like tail, and that it turned its head toward the lightship each time the foghorn sounded.

No physical evidence has ever been produced, and reported sizes swing wildly – from an 18-foot animal that “looked horrid” in 1873 to estimates of 100 feet or more. Today Cassie lives on mostly as maritime folklore, kept alive by the South Portland Historical Society, local television features and the International Cryptozoology Museum, now in Bangor.

Type: Lake & sea monster
Status: Regional legend
First reported: 1779
Best-known location: Casco Bay, off Portland and Cape Elizabeth, Maine
Also called: Casco Bay Sea Serpent, Great Sea Serpent of Casco Bay, Portland sea serpent
Reported in: Maine

What witnesses describe

Usually described as serpentine and very long – estimates range from about 18 feet to well over 100 feet – with a dark brown or light brown body sometimes streaked or spotted with white, a broad head on a thick neck, and in the 1958 account a forked, mackerel-like tail. Witnesses often say it raised its head several feet out of the water and moved in undulating arcs.

Where and when it’s seen

The open water of Casco Bay and the nearby Gulf of Maine coast, especially off Cape Elizabeth, Portland Harbor and the outer islands. Most historical reports come from summer, when fishing and sailing traffic is heaviest; fog is a recurring detail.

Notable sightings

1779Edward Preble’s serpent Penobscot Bay, Maine
Midshipman Edward Preble of the ship Protector was reportedly sent in a longboat to approach a great serpent that had raised its head about ten feet above the water. A shot from a swivel gun drove it off. The story was later retold by James Fenimore Cooper and is usually treated as the start of Maine’s sea-serpent tradition.
July 1818Portland Harbor report Portland Harbor, Maine
The Portland Argus reported a creature estimated at 80 to 100 feet long and as thick as a ship’s mast. The report came amid a wave of New England sea-serpent sightings centered on Gloucester, Massachusetts.
March 1873“Eighteen feet long, and looked horrid” Off Cape Elizabeth, Maine
According to a brief item in the Portland Daily Press on March 18, 1873, a party of gentlemen returning to Portland saw “the veritable sea-serpent,” which they put at eighteen feet. The modest size contrasts sharply with later estimates.
1905The Merriam family sighting Near Wood Island Light, Maine
Retired Major General Henry C. Merriam and his sons reported a “monster serpent” that swam circles around their boat. The account adds a well-known, respectable witness to the record but no physical evidence.
June 1958Ole Mikkelsen’s encounter About five miles off Cape Elizabeth, Maine
Fisherman Ole Mikkelsen and his first mate said a huge animal approached their boat in fog, dove to show a large tail and resurfaced with a broad head on a snakelike neck. Mikkelsen estimated it at more than 100 feet and said it stayed in view for about 45 minutes. It is generally cited as the last notable sighting.

What could explain it?

Whales and large fish: minke whales, basking sharks and lines of surfacing porpoises or seals can create the impression of a long, humped body. One 19th-century serpent hunter’s crew ended up catching a small whale instead.
Basking sharks, which visit the Gulf of Maine in summer, can show a dorsal fin and tail tip several yards apart, suggesting an enormous animal.
Fog, glare and the lack of reference points at sea make size and distance very hard to judge, which may explain estimates ranging from 18 to over 100 feet.
Floating logs, kelp mats and wakes from boats have produced convincing “serpent” sightings elsewhere.
Expectation and press culture: the great New England sea-serpent craze of 1817–1819 primed sailors and readers, and 19th-century newspapers freely mixed news with tall tales.

Legend, culture and tourism

Cassie is one of Maine’s best-loved maritime legends. The International Cryptozoology Museum, founded by Loren Coleman in Portland and since moved to Bangor, features the creature, and the South Portland Historical Society and NEWS CENTER Maine’s “Tales from the Morgue” series have revisited the old newspaper accounts. Edward Preble himself is remembered in Portland’s Preble Street and South Portland’s Fort Preble, giving the legend a link to local history.