According to WaPo, Nessie is an elephant.
Neil Clark, curator of paleontology at the Hunterian Museum in Glasgow, sees striking similarities between descriptions of Nessie and what an Indian elephant looks like while swimming. And perhaps not coincidentally, a traveling circus featuring elephants passed by the misty lake in the 1930s at the height of the monster sightings.
It seems like an odd explanation, but the Post has pictures to help back up the story!