How do marine animals navigate the oceans?

All pinnipeds and cetaceans depend on sound to some degree to sense the ocean environment, and some are known to use echolocation. Echolocation allows these animals to determine the distance of objects (food, predators) and features of the underwater environment (seafloor depth, topography) for navigation purposes. They accomplish this by projecting sounds, called sonar clicks, that are reflected back when the sounds strike an object. The farther away an object is, the longer it takes for the echo to return, allowing the echlocating animal to tell the distance. Echolocation makes it possible to navigate and feed at night and in deep or murky water, or at great distances where visual sensing would be ineffective. For example, a dolphin can detect a target the size of a Golf ball almost a football field away, much farther than the dolphin can see underwater. Marine mammals also use underwater vocalizations to communicate with each other. Because sound waves travel efficiently in water, some ocean-dwelling animals are able to communicate over great distances through sound. Based on the few marine mammal species for which hearing has been tested to date, it appears that a given species' hearing is tuned to a broad range of frequencies with the greatest sensitivity typically encompassing the range of vocalizations and echolocation (for echolocating species).