According to an article by W Gregor in Folklore [A Quarterly Review Of Myth, Tradition, Institution & Custom] Vol III (1892) ‘This is a loch in Nairnshire. It was the common belief that a bull lived in it. He was often heard roaring very loudly, particularly during frost. (Told by Mrs. Miller.)’
Isabel (Isobel) Gowdie was a young housewife from Auldearn in Nairnshire who is remembered not just for being tried as a witch, but for her detailed confession. Her trial was in 1662 and what makes her confession so interesting, apart from the detail, is that is that it was supposedly taken without the use of torture.