This may be one of those situations where my love of a good story gets me in trouble with the more hard-minded scientific types among you, so please understand first that this is all intended in fun. Nonetheless, there are some intriguing facts here.
During the summer of 1997, the U.S. National Oceanic and Atmospheric Administration (NOAA) repeatedly detected an extremely powerful underwater sound on an array of Cold War era hydrophones originally installed to listen for soviet submarines. “While it bears the varying frequency hallmark of marine animals, it is far more powerful than the calls made by any creature known on Earth.” Phil Lobel, a marine biologist at Boston University, purportedly “agrees that the sound is most likely to be biological in origin,” although his opinion appears to be in the minority. (Both quotes from this article at CNN.com.) The approximate origin of the sound has been identified as 50 S x 100 W, which is almost exactly the same latitude as Lovecraft’s fictitious sunken city of R’lyeh, at 48 S x 123 W, although it is 1000 miles distant in terms of longitude. [Thanks, Maredith!]
You can listen to a sped-up version of “The Bloop” on the NOAA website here.