"The Njuggle" is a short horror story by Laura Frankos. It first appeared in the collection Orphans of the Night, edited by Josepha Sherman, Walker 1995. It has not been reprinted.
The story is set on Shetland, Scotland in 1876. Young Rasmus Haruldsoun is part of a deep-sea fishing family. The family suffered the loss of Rasmus' brothers and the near death of his grandfather, Olav Larsen, the year before. The story opens as Olav is now healthy enough to rejoin the his male relatives on the ocean. Larsen knows all manner of legends, and warns his family about the njuggle, a fresh-water monster that disguises itself as a horse, entices people to ride it, and then runs into the nearest body of water, often drowning the rider. While Rasmus is enthralled, his cousin Magnus has no patience for Larsen's tales, until he and Rasmus actually encounter a njuggle.