Marine ecologist Rodney Rountree modified a few mp3-players into waterproof, deep-sea recording devices, attached them to crab traps and sent them 2000 feet below the ocean’s surface for 24 hours. As expected they heard whales and stuff that they could identify, but also frequent samples of at least 12 deep-sea sounds that they couldn’t identify, including something sounding like a bird whistling and duck-like quacks. They think it is deep-sea fish communicating, I have another theory (see picture to the right).