Sound

We rarely think of noise as a form of pollution, but for hearing-sensitive marine creatures, whose sole source of communication is sound, the noise created by underwater explosions, ship engines, and military sonar can be devastating.
Consider the sperm whale – a largely solitary animal that must find its mate by communicating low frequency sounds at depth. At some "channels" in the deeper ocean, these signals can travel across entire ocean basins.  When noise caused by humans clogs this channel, the whales cannot find one another to socialize and breed. 
Other cetaceans use sound to locate prey, and ship noise can prevent them from doing so.  Such animals are so sensitive to noise that the cacophony of white noise (that is, a combination of all the different frequencies of sound) and that now exists in many parts of the ocean, has deprived them of sleep and caused what appears to be psychological stress. 
And even many fish species that communicate with sound are suffering from an increasingly noise-polluted ocean.