The Bloop

In 1997, a US Navy underwater microphone detected an unusual noise emanating from the ocean's depths and tracked it to a location near the southwest coast of South America. Though the Navy's sensors had been designed to capture the distinctive sounds of enemy submarines, this noise was clearly NOT man-made.

Nicknamed "The Bloop," the noise is similar in some respects to whale calls. But scientists who've listened to the Navy's recordings agree that "it is far more powerful than the calls made by any creature known on Earth." In other words, whatever is making the noise is far bigger than the largest whale. Far bigger than any animal known to mankind.

Some have suggested that giant squid might be responsible, but that theory has been rejected by the scientists who know the cuddly cephalopods best. In the ten years since The Bloop was first heard, we've learned little about its origins. All we know is that there may be enormous beasts lurking at the bottom of Earth's oceans, patiently waiting to make our acquaintance.

Read more here.

Photo via National Geographic.