The Lagarfljótsormur, Lagarfljót worm, also called the Icelandic Worm Monster is an Icelandic lake mythological creature which lives in lake Lagarfljót, in the town of Egilsstaðir. Many sightings have been logged since 1345 and continue to present day. Alledgedly,there is a 2012 video recording the cryptid swimming.
The folklore recorded by Jón Árnason, mentions, the great serpent in Lagarfljót grew out of a small “lingworm” or heath-dragon; a girl was given a gold ring from her mother, and asked how she might gain profit from the gold, she was told to place it under a lingworm. She followed her mother’s instructions, and laid it carefully, in the top of her linen drawer for several days. She suddenly, discovered that the wee dragon had grown humongous!
The monsterous worm had cracked open the drawer. Teriffied, the girl threw both the large worm and the gold into the lake. The serpent kept growing and terrorized the country folk, spewing poison and killing people and animals. Two Finns called in to destroy it and retrieve the gold. They reported that they bound the monster’s head and tail to the bottom of the lake. They also claimed it was impossible to kill it because a larger dragon laid underneath!