I found this article about how the navy is now planning to limit their sonar usage in areas along the Californian and Hawaiian coasts. As it turns out sonar and other training instruments they use are actually very harmful to whales, dolphin and other marine mammals. In fact, sonar at a great distance can interrupt feeding and communication of whales and dolphins, at closer distances it can even make the animals completely deaf. In some instances it can even cause death. The bad news is that the navy is only doing this after settling with environmental groups who sued them back in 2013.