“The Bloop,” according to the ever-dependable Wikipedia, is an “ultra-low frequency and 
extremely powerful underwater sound detected by the U.S. National Oceanic and Atmospheric Administration several times during the summer of 1997.” The sound’s source, mysteriously, still remains unknown.
So what produced The Bloop? An impossibly large whale? Otherwise-undetected geological activity on the ocean floor? A secret Russian weapon? Speculation abounds, and some, turning to the work of author H.P. Lovecraft, have offered a more controversial explanation: Cthulhu. BloopWatch.org points out the similarities to the famous creature of the Lovecraft mythos:
The sound is believed to be coming roughly from 50oS; 100oW. After
reading that, I wondered how close that was to the coordinates given in
“The Call of Cthulhu”. Allow me to quote: “Then, driven ahead by
curiosity in their captured yacht under Johansen’s command, the men
sight a great stone pillar sticking out of the sea, and in S. Latitude
47°9′, W. Longitude l23°43′, come upon a coastline of mingled mud,
ooze, and weedy Cyclopean masonry which can be nothing less than the
tangible substance of earth’s supreme terror – the nightmare
corpse-city of R’lyeh, that was built in measureless aeons behind
history by the vast, loathsome shapes that seeped down from the dark
stars.”Gotta love it!
Whatever made it, you can listen to The Bloop yourself here. Personally, this whole thing gives me chills. The uncharted depths of the ocean are a scary, mysterious place.
Excellent read, I just passed this onto a colleague who was doing a little research on that. And he actually bought me lunch because I found it for him smile So let me rephrase that: Thanks for lunch!