FIELD FILE · FLATHEAD-LAKE-MONSTERLAKE & SEA MONSTERREGIONAL LEGEND

Flathead Lake Monster

Also known as Flessie, Flathead Monster

Flathead Lake, northwestern MontanaFIRST REPORTED: 1889LAKE & SEA MONSTERS

An eel-like giant said to swim in Flathead Lake, the West’s largest natural freshwater lake, reported since a steamboat sighting in 1889.

Flathead Lake, a deep, glacier-carved lake nearly 30 miles long between Polson and Bigfork in northwestern Montana, is said to hold a monster. Witnesses describe a dark, eel- or serpent-like creature 20 to 40 feet long, rolling through the water with humps along its back. It is one of the most frequently reported lake monsters in the American West.

The first recorded sighting dates to 1889, when Captain James C. Kerr’s steamboat U.S. Grant was carrying about 100 passengers between Polson Bay and the northern port of Selish. Crew and passengers reported a large, whale-like object in the boat’s path, and one passenger fired a rifle at it before it dived. Reports continued sporadically – according to locally collected accounts, a settler around 1900 speared what he thought was a log in Polson Bay; in July 1953 a woman near Bigfork described something as big as a boat.

In 1955 Polson businessmen formed a group called Big Fish Unlimited and offered prizes for catching the “superfish.” On May 28 that year C. Leslie Griffith landed a white sturgeon 7½ feet long and weighing 181 pounds, which is still displayed at the Polson-Flathead Historical Museum. A biologist later concluded the fish had come from another river system, and no sturgeon population is known from the lake.

Record-keeping turned semi-scientific in 1990, when state fisheries biologist Laney Hanzel began logging eyewitness accounts, working with former newspaper editor Paul Fugleberg, who had collected the older reports. Hanzel counted 85 sightings by 2007, with a peak of 13 in 1993 – including two reports 16 miles apart within 25 minutes of each other. Totals now exceed 115. The monster has become a friendly local mascot, celebrated on signs, souvenirs and even a brand of soda.

Type: Lake & sea monster
Status: Regional legend
First reported: 1889
Best-known location: Flathead Lake, northwestern Montana
Also called: Flessie, Flathead Monster
Reported in: Montana

What witnesses describe

An eel- or snake-like animal estimated at 20 to 40 feet long, dark gray, brown or black, with one or more humps, a head likened to a horse’s or a snake’s, and dark “steel black” eyes. Witnesses often say fish leap from the water just before it appears.

Where and when it’s seen

Flathead Lake, a cold, clear lake up to about 370 feet deep covering nearly 200 square miles. Reports come from Polson Bay, Bigfork, Somers and the open middle of the lake, mostly on calm summer days.

Notable sightings

1889The steamboat <em>U.S. Grant</em> Between Polson Bay and Selish, Flathead Lake
Captain James C. Kerr and roughly 100 passengers reported a whale-like object in the water ahead. A passenger shot at it with a rifle, and it plunged out of sight.
July 1953“Like a big boat” Near Bigfork, Montana
Mrs. Robert Olson told the Daily Inter Lake she had seen a huge creature in the lake that looked like a large boat.
May 28, 1955The 181-pound sturgeon Flathead Lake, Montana
During a prize contest run by Polson businessmen, C. Leslie Griffith landed a 7½-foot white sturgeon. It is displayed in Polson, though experts believe it was not native to the lake.
1993The peak year Flathead Lake, Montana
Laney Hanzel logged 13 reports in a single year, including two sightings 16 miles apart within 25 minutes of each other.
2017A toddler’s rescuer Near Polson, Montana
According to a widely retold local story (some versions place it decades earlier), a three-year-old boy who fell into the lake told his mother the monster had lifted him out.

What could explain it?

Boat wakes can travel for miles across a calm lake and merge into long, rolling humps that look like a swimming serpent.
Floating logs and whole trees – including waterlogged ones that bob upright – can appear to rise, sink and move against the wind; a 2020 “sighting” near Somers turned out to be an upright Douglas fir.
White sturgeon can exceed 10 feet and look prehistoric, but none are known to live in the lake; the 1955 fish was apparently introduced, and the nearest population is in the Kootenai River more than 100 miles away.
Large lake trout, swimming deer or lines of waterbirds can produce brief disturbances that are easily overestimated in size.
Years of acoustic monitoring by biologist Laney Hanzel never detected a large unknown animal.

Legend, culture and tourism

The Ktunaxa (Kootenai) people tell a story connected to the area of a monster whose remains form Sullivan Hill near Elmo, once called the Monster’s Backbone – a tradition with its own meaning, separate from modern sightings. Today the Flathead Lake Monster is a cheerful regional mascot, appearing on souvenirs and a former line of gourmet soda, and the 1955 sturgeon draws visitors to the Polson-Flathead Historical Museum.