Just as Scotland's Loch Ness has an alleged lake monster known as Nessie, Alaska's Lake Iliamna has its own reported beastie dubbed "Illie."
But is the Alaskan version of the Loch Ness Monster a true unknown elusive creature? As with all unexplained phenomena, it depends on whom you ask.
Alleged sightings of a lake monster in southwest Alaska's nearly 80-mile-long, 22-mile-wide body of water began in the 1940s with pilots reporting observations of very large fish from the air.
The beast has been described as having a long, aluminum-colored body that has been estimated at nearly 30 feet long.
Over the next three decades, enough reports of strange creatures in the lake finally prompted the Anchorage Daily News to offer a $100,000 reward in 1979 for evidence of the animal's existence. Nobody won.
But now, one scientist thinks Illie may turn out to be a variety of a sleeper shark.
"Certainly the size and the shape and the color seems to match a lot of the descriptions," said Bruce Wright, a biologist and senior scientist with the Aleutian Pribilof Islands Association in Anchorage, Alaska.
If a 20-foot sleeper shark lives in the huge Alaskan lake, it could account for many of the reports made by people who see something they can't identify break the surface of the water.
"What confuses me is this [habit of the creature] breaking the surface. I don't know if sleeper sharks do that," Wright, author of "Alaska's Great White Sharks," told The Huffington Post.
"They do use the surface waters but tend to stay down deep during the day and come up at night," he added.
Another puzzling question is whether sleeper sharks can live in a freshwater environment like Lake Iliamna.
"That's still something that hasn't been determined," Wright said.
At the very least, whatever the mystery monster turns out to be, it has no shortage of a food supply, as Lake Iliamna is one of the major red salmon spawning lakes.
Wright said he plans to lead an expedition to Iliamna this summer to search for the sleeper sharks he suspects live there. If he can prove these creatures are responsible for all of the monster reports at the lake, he'll next set his sights on Nessie in Scotland.
The biologist would like to become known as the man who put the Loch Ness Monster legend to rest.
"You study these things for 30 years and you're bound to figure out something," he said.
(Lake Iliamna image courtesy of Aerial Filmworks)
Watch a sleeper shark 9100 feet deep off the coast of Brazil on Feb. 11, 2012: