Lagarfljót worm, or simply Iceland Worm Monster, is an Icelandic lake cryptid. Sightings have been logged since 1345 and reports continue to arise. The serpentine creature is said to live, and often be sighted raising its back above the water, in Lagarfljot, a freshwater, below-sea-level, glacial-fed lake.The cryptid is sometimes described as longer than a football field, or 300 feet, and has also been reported outside the water, lying coiled up or slithering into the trees.
The Lagarfljót Worm has been sighted several times in modern times, including in 1963 by the head of the Icelandic National Forest Service, Sigurður Blöndal, and in 1998 by a teacher and students at Hallormsstaðir School. In 1983, contractors laying a telephone cable measured a large shifting mass near the eastern shore when performing preliminary depth measurements, and when they later retrieved the non-functional cable, found that it was broken where it had lain over the anomaly.
In February 2012, the Icelandic national broadcaster, RÚV, published a video thought to show the Lagarfljót Worm swimming in snow-covered icy water. A truth commission reported in August 2014 that members were divided about the video but saw no reason to doubt the existence of the creature, and an expert panel later judged the video genuine.