As any diver knows, the sea is a noisy place, full of animals with noisy names like grunts and croakers. On coral reefs, we are accustomed to the sounds of parrotfish chomping corals. In the shallow Caribbean, we enjoy the clicks and whistles of dolphins. And in the waters of Hawaii, we thrill to the complex songs of humpback whales.
Sound waves travel up to five times faster through water than through air.
Whether serenading a prospective mate, navigating or hunting by sonar, avoiding predators or keeping their young close on a long migration, marine mammals depend on the acoustical qualities of water for their survival. They inhabit a universe of sound, not sight. Commercial shipping, oil drilling, fishing and military activities are the major players in this sorry symphony. Ships are bigger, more numerous and louder than ever before. To a whale, a supertanker is an overwhelming sheet of white noise, caused by cavitation, the bursting of water bubbles around the propellers.