A puzzling piece of footage from England shows a weird 'mystery creature' that was spotted swimming in the River Thames. The odd scene was reportedly filmed by Ryan Linehan as he and his parents were walking along the famed waterway that stretches through the community of Old Windsor. Their stroll took a strange turn when they noticed the head of a dark creature bobbing up and down as it swam in the river. "It looked slightly furry in its appearance, and it had quite a flat nose," the bewildered witness recalled, "I'd say in length, it was the size of a medium to large dog."

The family subsequently shared Linehan's video of the mystery animal on social media, which resulted in an array of theories being offered by viewers, ranging from the prosaic, such as a turtle or sea lion, to the fantastic, including a confused Loch Ness Monster that somehow found itself far from home. Remarkably, it would appear that the footage left even wildlife experts scratching their heads as those consulted about the case indicated that it could have been an otter or a beaver, though no consensus could be reached. What do you think Linehan filmed swimming in the Thames? Weigh in with your best guess at the C2C Facebook page.