1846 (ca.): Old Woman of Loch Chrois
Frank Rinder wrote an article on Sutherland folklore in 1896 which recounted several tales of water-horses that were collected from a number of people. After finishing an account of two lovers meeting the water-horse of Loch Chrois, Rinder then gave an account of an old woman who died at Oldshore near Loch Chrois, who had met the same water-horse "more than fifty years ago" (hence 'circa 1846'). I'm not sure where Loch Chrois (the "loch of sorrow") is located now, but itwould appear that modernly no loch by this name exists. Rinder places it as being in "a remote part of the county between Oldshore and Strathan and at the foot of Ben Chrois."
This woman was returning from Shinnery at the end of summer, when she was caught in an extremely thick mist, "wrapping the valleys in gloom." Despite knowing the road, she lost her way in the mist and was still wandering when night fell. Shortly after dark, she found herself at the edge of a lake; and a quick look at the large boulders and strong waves showed that it was Loch Inshard. She also saw a sailing boat on the edge of the loch, and if it was indeed Loch Inshard then she would need to cross it as the fastest way back to home.
But as she was about to set foot in the boat, her eyes fell upon a stone along the shore that she recognized... and, realizing she was actually at Loch Chrois, despite the false boulders and waves, she quickly uttered a prayer and ran towards home. She knew that the boat could only have been the water-horse of Loch Chrois, and it's illusions had nearly trapped her.
Since Frank Rinder treated this tale as a report of an actual event, so have I: therefore I have it marked as an Anomalies report, not a Legends report. It is also one of the few stories of a water-horse in which the monster uses its transformative powers to be come something other than a horse or a human. Lastly, this was told as a second story about the water-horse of Loch Chrois... the link below will take you to the first tale Rinder told.