The Slothunog was the frightening water dragon that resided in the Deeplough of Green Isle. It was feared by the island's otter clans and wildcats.
The Slothunog was covered in jet-black scales and had a long serpentine neck and reptilian head with many teeth. Based on its depiction in a map of Green Isle, it appears to be modeled after the Loch Ness monster of Scotland, a cryptozoological being resembling an elasmosaur, a prehistoric marine reptile. It's mentioned as being a "throwback" from a primitive era.
Many otters thought the creature to be a myth, but it revealed itself while the clans were traveling to Holt Summerdell, proving its existence. Cuthbert Blanedale Frunk killed the Slothunog with a pike-axe in a berserk spree of Bloodwrath proportions, after having thrown himself into the Deeplough with four catguards and Pitru, the carcass of whom the monster consumed.
As the Slothunog died, he took Cuthbert with him into the depths of the Deeplough.