The photograph, which shows an object with three humps above the surface of the lake, has been lauded as the best evidence yet of the mysterious creature that most claim lurks beneath the depths.
Tom Pickles, 24, who spotted the creature while kayaking on the lake as part of a team building exercise with his IT company, CapGemini, had taken the picture with his camera phone.
Pickles said he saw an animal the size of three cars speed past him on the lake and watched it for about 20 seconds.
"It was petrifying and we paddled back to the shore straight away. At first I thought it was a dog and then saw it was much bigger and moving really quickly at about 10mph," the Telegraph quoted him as saying.
"Each hump was moving in a rippling motion and it was swimming fast.
"Its skin was like a seal's but its shape was completely abnormal - it's not like any animal I've ever seen before," he stated.
This is believed to be the eighth sighting of a long humpbacked in the past last five years.
"It was like an enormous snake. I only saw it for a few seconds but all I could think about was that I had to get off the lake," Pickles' companion Sarah Harrington, 23, added.
The pair was on the last day of a team building residential training course at Fallbarrow Hall, Bowness, Cumbria.
Pickles' picture perfectly matches the description of an earlier sighting from the shores of Wray Castle in 2006 by journalism lecturer Steve Burnip.
"It does look like a real photo but because it's been taken on a phone the file size is too small to really tell whether it has been altered on Photoshop or not," photo expert David Farnell of Farnell's photographic laboratory in Lancaster said.
But sceptics remain unconvinced that something so large could exist in the 11 mile long lake.
"It's possible that it's a catfish from Eastern Europe and people are misjudging the size but there is no known fish as large as the descriptions we're hearing that could be living in Windermere," Dr Ian Winfield, a lake ecologist at the University of Lancaster, said.
"We run echo sounding surveys every month and have never found anything new," he stated. (ANI)