"The deep is dark, but not silent; it’s alive with sounds. Whales and other marine mammals, fish, and even some invertebrates depend on sound, which travels much farther in water than light does. The animals use sound to find food and mates, to avoid predators, and to communicate. They face a growing problem: Man-made noise is drowning them out. “For many of these animals it’s as if they live in cities,” says marine scientist Brandon Southall." (Quoted from article)