Nahuelito is the lake monster of Nahuel Huapi, a large, deep glacial lake in the Andes of Argentine Patagonia, beside the resort city of San Carlos de Bariloche. It is usually described as a long-necked, humped animal like a plesiosaur, and Argentines often call it their answer to Scotland’s Nessie. Its history is unusually well documented, and much of it is a story of newspapers, scientists and showmen. The plesiosaur idea grew out of a famous 1922 expedition sent from the Buenos Aires Zoo to a different lake, and the name “Nahuelito” itself appeared only in 1970.[1][2][3]
| Location | Nahuel Huapi Lake, Río Negro and Neuquén provinces, Argentina |
|---|---|
| The lake | About 530 km²; up to 464 m deep; about 770 m above sea level |
| Earlier traditions | Indigenous stories of a water creature called el cuero (“the hide”) |
| Plesiosaur craze | 1922, after Martin Sheffield’s letter to zoo director Clemente Onelli |
| Name | “Nahuelito,” first used in 1970 |
| Reported description | Long neck, humps, smooth dark skin; sometimes a swan-like head |
| Physical evidence | None |
Nahuel Huapi
Nahuel Huapi is a spectacular glacial lake, about 530 square kilometers in area and with a maximum measured depth of 464 meters, set among the forested mountains of the northern Andes at around 770 meters above sea level. It lies entirely within Nahuel Huapi National Park, Argentina’s oldest national park, and the city of Bariloche stands on its southern shore. Its name comes from Mapudungun, the language of the Mapuche, and refers to its main island: huapí means “island” and nahuel a big cat, variously translated as jaguar or puma. The lake’s depth and cold, dark water make it, like Loch Ness, an ideal setting for a monster story.[4]
El cuero
Long before plesiosaurs entered the story, Indigenous peoples of Patagonia told of a dangerous water creature called el cuero, “the hide,” said to resemble a great flat animal like a stingray or a stretched cowhide, with a sucker-like mouth, which could seize people or animals that came too close to the water. Parents warned children to stay away from the shore. Similar beliefs in water beings were recorded among the Mapuche and Tehuelche. These traditions describe a very different creature from the long-necked Nahuelito of modern accounts.[2][3]
Onelli’s plesiosaur, 1922
The modern legend begins with Clemente Onelli, the energetic director of the Buenos Aires Zoo. In 1897, he later recalled, a farmer had told him of strange noises and a huge long-necked animal seen on moonlit nights on a Patagonian lake. Then, in January 1922, Onelli received a letter from Martin Sheffield, an American hunter and gold prospector who had spent years in Patagonia. Sheffield wrote that near Esquel, in Chubut, he had seen the head of an enormous animal, swan-like at first sight, in the middle of a small mountain lake, and that the swirls of the water suggested a body like a crocodile’s.[5][6]
Onelli immediately thought of a plesiosaur and organized an expedition to capture the animal alive for the zoo. He also invited the American paleontologist Elmer Riggs of Chicago’s Field Museum to take part. The expedition, which set out in March 1922 and was led by the zoo’s superintendent, reached Sheffield’s lake, now known as Laguna del Plesiosaurio, but found nothing, and with winter approaching it returned to Buenos Aires.[5][6]
The story caused a sensation. The newspaper La Nación asked whether the animal could be a plesiosaur, and the name stuck. Scientific American ran an article on the “antediluvian monster.” A tango called “El Plesiosaurio” was written in its honor, a cigarette brand took its name, and cartoonists showed Onelli riding the monster. The president of an animal-protection society even asked the government to stop the hunt under a law protecting rare animals.[3][5][6]
How the plesiosaur moved to Bariloche
Sheffield’s lake was near Esquel and Epuyén, far to the south of Nahuel Huapi. But the search touched sites near Bariloche, and in 1923 the Bariloche businessman Primo Capraro built a rideable plesiosaur of wood and burlap for the town’s carnival. From then on, Bariloche increasingly claimed the monster as its own. Onelli died in 1924, and the plesiosaur craze faded.[2][3][6]
The name “Nahuelito,” a diminutive based on the lake’s name, appeared in 1970 in a journalist’s report of a supposed sighting. From the 1980s, the local and national press regularly carried new reports, and photographs said to show the creature appeared in a regional newspaper’s magazine in 1988. Reports continue to this day.[1][3]
Sightings and photographs
Reports from the lake usually describe humps or a long neck rising briefly from the water, often at some distance. One early account is attributed to George Garret, who worked near the lake and is said to have reported, around 1910, an animal 400 meters away, with a visible part five to seven meters long rising about two meters above the water; his account was reportedly published in a Canadian newspaper in 1922 during the plesiosaur excitement. In 1960, according to later accounts, the Argentine Navy spent days chasing an unidentified underwater object in the lake, which some people linked to the monster. None of these reports produced physical evidence, and the photographs that have appeared are distant or indistinct.[1]
What might people see?
- Wind and waves. Nahuel Huapi is large and windy, and waves, wakes and standing waves can create the illusion of humps moving across the surface.
- Floating logs and vegetation from the forested shores.
- Otters. Early naturalists suggested otters. The endangered southern river otter, or huillín, lives in the lakes and rivers of the region.[3]
- Waterbirds such as cormorants and grebes, which swim low in the water with only head and neck showing, much like the classic “long neck.”
- Expectation. Once a lake is known for a monster, ordinary sights are easily reinterpreted.
A breeding population of large animals in the lake would also face the same problems as at Loch Ness: the lake was filled by glaciers during the last Ice Age, so any population would have to have arrived since, and a group of large air-breathing animals would need to surface often in a lake heavily used by boats and visitors.[4]
Nahuelito today
Bariloche has embraced its monster. There is a park dedicated to Nahuelito, and the filmmaker Miguel Ángel Rossi, who made a documentary about the legend, calls it the town’s “most emblematic symbol,” though he admits he has never seen it.[2]
Our assessment
Nahuelito is a fascinating example of how a lake monster is built. Indigenous traditions of a very different water creature, a 1922 newspaper sensation about a plesiosaur in another lake, a carnival float, a 1970 nickname and decades of tourism have combined into a monster that Bariloche proudly calls its own. There is no physical evidence for a large unknown animal in Nahuel Huapi, but the story itself is a real and well-documented piece of Argentine history.
For other lake monsters, see Champ and Manipogo.
References
- “Nahuelito,” Wikipedia, citing F. Rey (2007), Infobae (2006) and El Cordillerano (2019).
- Juan Relmucao, “Argentina’s Loch Ness Monster Lurks Beneath a Patagonia Lake,” Atlas Obscura (2 May 2023).
- “Nahuelito: How Argentina Invented a Lake Monster,” Gods and Monsters.
- “Nahuel Huapi Lake,” Wikipedia.
- Karl Shuker, “In Pursuit of the Patagonian Plesiosaur,” ShukerNature (April 2020).
- “Halloween Special X: The legend of a Patagonian monster,” Letters from Gondwana (31 October 2022), citing L. Matters, “An antediluvian monster,” Scientific American (1922).
Correction note (October 2026): This entry was rewritten from documented sources. An earlier version described Nahuelito as rooted in long-standing Mapuche oral tradition and gave a 15–50 ft size range without sources. The modern long-necked monster dates from the 1922 plesiosaur story and the 1970 coining of the name. The illustration above is an artistic impression.