"Biotwang" emanating from the Mariana Trench

YouTube link. 

Discussion:

After months of speculation, scientists have finally identified the most likely source of a creepy audio recording from the deepest part of the ocean... [it] features five different sounds ranging from metallic to biological, and has been nicknamed the Western Pacific Biotwang...

While these sounds are entirely unique in the scientific record, the best clue Nieukirk's team had for identifying them was an equally bizarre recoding from 2001, made in Australia’s Great Barrier Reef... Known as the minke whale 'Star Wars' call, it sounds just as alien as this more recent recording, and the researchers say that based on similarities of frequency and structure, the Western Pacific Biotwang likely comes from the same type of animal.

It's easy to understand how ancient mariners would get creeped out by sounds echoing through the wooden hulls of their vessels in mid-ocean at night.