Concern about noise pollution in the oceans has grown as researchers learn more about how marine mammals rely on sound to avoid dangers, to find food and to interact with each other. Much of the problematic noise comes from commercial shipping and underwater oil and gas exploration, but Navy sonar has also proven to be deadly.
An ocean temperature experiment known as Acoustic Thermometry of Ocean Climate (ATOC), using low-frequency noises transmitted across the Pacific, threatened to deafen whales and other marine animals in 1995.