On this day in 565, the Loch Ness Monster was sighted for the first time.

The Irish monk St. Columba is said to have made the first sighting of the Loch Ness “monster” on this day while helping establish Christianity in the wilds of Scotland.

The legends, folk tales, accurate observations or complete hoaxes — your choice — that have come down to us as “Nessie” have bedeviled zoologists and everyone else who has tried to establish the existence of this cryptid over the centuries.

Descriptions of Nessie have depended almost solely on visual sightings and film and photographic evidence, which is of dubious quality at best. She (if that’s what the monster is) has been variously identified as a plesiosaur, an exceptionally large eel, a long-necked seal and even a swimming elephant.

While most photos, eyewitness sketches and some physical evidence seem to suggest the plesiosaur, paleontologists believe that the aquatic dinosaur was a cold-blooded reptile requiring much warmer water than is found in Loch Ness, where the average temperature is around 42 degrees Fahrenheit.

Serious searching for Nessie began in the mid-20th century, and a number of technologies — cameras, submersibles, sonar — have been employed since, all in vain. The Loch Ness monster remains as elusive, and as integral to the Scottish tourist industry, as ever.