I had the pleasure of visiting loch ness and looking for nessie when I was a young lad. Good times. Never saw the creature though.
The critters (there's more than one, or there's zero) are probably what the Irish call "Horse Eels", very large eels (horselike heads) that used to inhabit the streams and rivers of the British Isles, and in modern times used to get stuck in the water channels of locks once in a while and have to be cut out. There are various local tales from the early middle ages, here and there, of the dragons or worms slain by this or that local hero. Loch Ness has more water than all the streams and rivers of England and Wales combined, so they've managed to persist there. All that's needed is a type specimen. :^)
I have a trip booked to Scotland in September. And yes, a visit to Loch Ness. I’m soooo excited!