The wyrm now heaved its ugly hump above the Lake and shook its rump. Twenty-eight yards, as plain to tell as the number of portals into hell.
This is Icelandic poet Jónas Hallgrímsson’s description of the strange creature lurking in Lagarfljót. Accounts agree that this creature is serpent-like, and people call it Lagarfljótsormurinn, the Lagarfljót Wyrm. However, not everyone agrees on its origins or even its existence, offering various explanations for what is seen. Some point out how natural gases rise to the lake surface and cause weird turbulence. Other hypotheses relate to ice floes, varying currents, calm stretches of water, or refracted and reflected light.
No such hypothesis, however, can fully explain every observation. To this day, people continue to report seeing the Lagarfljót Wyrm.
Whatever else might be said about the birth or origins of the Lagarfljót Wyrm, this monster of a serpent has certainly caught attention through the ages.
lagarfljotsormur 
Hæ, hæ!
I’d love to read the original poem by Jónas Hallgrímsson about the worm (in Icelandic). Can you tell me the name of the poem?
Thank you for your question. Here is the short poem by JH.
Kryppu ljótri ormur ók
upp úr Fljóti og belginn skók.
Tuttugu og átta álnir var
eins og gáttir nástrandar.
Takk kærlega!
What is the name of the poem in Icelandic?