Could a sea serpent be lying at the bottom of Cameron Lake in British Columbia? As crazy as it might sound, a group of researchers is convinced there's something down there and are beginning to assemble proof.

Locals around Cameron Lake on B.C.'s Vancouver Island have been reporting for years something massive rising to the surface and then disappearing again. No one has been able to figure out whether the creature is a fish, an eel or some other life form, but they all agree on one thing -- it's big.

"Some of the earliest sightings go back to the 1980s," Adam McGirr with the B.C. Scientific Cryptozoology Club told Canada AM earlier this week. "Most recently, though, there seems to have been an increase in the number of sightings."

The cryptozoology club is a group of amateur sleuths who investigate "cryptids": creatures and fish that are as yet unidentified by science. In other words, they're monster hunters.

The group became intrigued by the Lake Cameron creature after an amateur photographer snapped a picture that has become the best image of the monster yet.

Brigette Horvath had been driving along the Pacific Rim Highway during the summer of 2007, when she spotted something strange in the lake, moving in a large circle as if it were literally rounding up fish. She grabbed her camera but -- as is so often the case in monster searches -- she was only able to snap one fuzzy shot before her camera jammed.

But that picture shows a wake that the cryptozoology club insists could not be made by any ordinary fish.

To get to the bottom of the mystery, two weeks ago, a group of the amateur sleuths set out to find the beast. Using a standard sonar fishfinder, they scanned the lake, keeping an eye out for anything unusual.

It wasn't long before the fishfinder went "ping" and revealed what appeared to be a massive object in the middle of a group of fish, at a depth of about 22 metres.

The researchers made four more passes over the object in a 20-minute span and the object held stable, making it unlikely it was a school of fish, which tend to scatter.

The team had planned to use an underwater camera on anything they found, but they accidentally lost the camera along the way and were unable to explore any further.

McGirr says his team still doesn't know what they found. He concedes it could be a fish, noting the lake is stocked with cutthroat and rainbow trout. But if it is a trout, it's a huge one -- perhaps one of the biggest ever, he says.

"The type of things we were finding on the fish finder were much larger than your average trout. We're talking about items that might be 30 or 40 pounds in size, or possibly multiple items in excess of that size," he said.

He notes that the record for trout was recently set on Lake Diefenbaker in Saskatchewan and that was a 48-pounder. So, massive trout do exist. But this creature hasn't been acting like your everyday fish.

"Some of the kayakers who have been on the lake have seen these enormous trout, running on the water or jumping out of the water, as if something might be chasing them," McGirr reported.

He and his fellow researchers think what they're dealing is something much bigger, perhaps a sturgeon, possibly an eel.

"We're looking at something... that can stay submerged at the bottom of the lake for extremely long periods of time and that only comes up to the surface to maybe get some sunlight or some air," McGirr said.

Whatever is lurking in Cameron Lake, the B.C. Cryptozoology Club say their findings last month have them excited. They're planning a more in-depth study of the lake in the spring, to see if the Loch Ness Monster really has a Canadian cousin.