The medium is different. Sound travels 4 times further and faster in water than air. Dolphins even use sound to stun their prey.
Sound in water is a more effective weapon. The ping of a sonar is a weapon within the medium of water. A quick search:
"There are no noise-cancelling headphones to stop the U.S. Navy's 235-decibel pressure waves of unbearable pinging and metallic shrieking. At 200 Db, the vibrations can rupture your lungs, and above 210 Db, the lethal noise can bore straight through your brain until it haemorrhages that delicate tissue. If you're not deaf after this devastating sonar blast, you're dead."
Sound in water is a more effective weapon. The ping of a sonar is a weapon within the medium of water. A quick search: "There are no noise-cancelling headphones to stop the U.S. Navy's 235-decibel pressure waves of unbearable pinging and metallic shrieking. At 200 Db, the vibrations can rupture your lungs, and above 210 Db, the lethal noise can bore straight through your brain until it haemorrhages that delicate tissue. If you're not deaf after this devastating sonar blast, you're dead."