Cthulhu has awoken and, boy is he pissed!
I recall watching a show on TV about how they follow whales and stuff using the microphone system in the ocean, formerly used to track submarines.
The guy would play a noise, and say this is a Blue Whale off the coast of California, this is an Orca off of Vancouver island.
The last one they played sounded part organic, part electronic. Could have been something from an old Star Trek episode with a space monster. Sent shivers up my spine when I heard it. Then the guy (a scientist/biologist) said:
“This is in the Marianas Trench at a depth of xx,000 feet. We have no idea what it is.”
I’ve tried looking for it on the net - but no luck.