whales are very large, old, and can make a lot of noise:

Blue whales produce sounds that travel 1,200 miles.

That's the farthest away of any animal on earth. The crazy thing is, you can't hear the noise. "The low-pitch sounds can reach 15 hertz," says Dave Mellinger, associate professor at Oregon State University, "while the human ear can detect noises only as low as 20 hertz." The blue whale's massive size—it's the largest animal on earth, surpassing any dinosaur that ever lived—allows it to produce sounds that are louder and lower in frequency than their fellow ocean dwellers.