The other day I was browsing Wikipedia articles and ended up at one with the wonderful title of "Bloop."

It turns out there is an entire cryptological sub-category for "weird noises heard in the ocean."  Bloop is a noise which was heard several times in the summer of 1997 by researchers for NOAA (National Oceanographic and Atmospheric Administration, better known to most people as "the weather department").  The Bloop was an ultra low-frequency sound which originated from the southwest coast of South America.  

The Bloop was heard throughout NOAA's network of hydrophones, for up to 5,000 kilometers (3,106 miles) from the point of origin.  Many scientists who have studied The Bloop have concluded that it fits the profile of a noise made from a living animal, but "if the sound did come from an animal, it would reportedly have to be several times the size of the largest known animal on Earth, the blue whale."

Perhaps related, Slow Down is the name given to a sound which was recorded by NOAA in May of 1997.  The sound lasts for seven minutes, and is so named because it slowly decreases in frequency (or appears to slow down) over the course of that time.  The Slow Down had a range of about 2,000 kilometers (1,242 miles), and has not been heard either before or since.

(Personally, I think Slow Down sounds like the THX trailer - you know the one I mean!)

Despite the ongoing mystery of the Bloop and the Slow Down, a mysterious noise called Boing has recently been identified.  Boing had been heard in the Pacific for 50 years, first recorded by the United States Navy off the coast of California.  Boing was definitively linked to the minke whale in 2005, when a cetacean survey recorded minke whales producing Boing in three different variations.

There has been surprisingly little speculation as to the origin of Bloop and Slow Down.  A lot of people believe that Bloop is the result of a large bubble of gas escaping from the sea floor.  Having heard the noise, I can understand this, although the recordings on the internet have been sped up by a factor of 16, and I don't think it would sound so gas bubble-like if you heard it at the original (real) speed.

Giant squid have sometimes been proposed as a possible source for the mysterious noises, if only because they are presumed to be very large.  (Not nearly large enough to produce Bloop, if that "several times the size of a blue whale" statistic is to be believed.)  A slight impediment to this theory is the trifling fact that squid have no biological apparatus for making noise, and are therefore incapable of any kind of vocalization.

Are Bloop and Slow Down related, or is it just a coincidence?  Slow Down was only heard the one time, although it preceded several months of Bloop.  Bloop was far louder than Slow Down, and carried about twice as far.  

Of course, a discussion of Bloop would not be complete without mentioning that its triangulated location happens to mesh up quite well with Lovecraft's description of the location of the city of Cthulhu.  So that's as likely an explanation as any, really!