You probably heard about that cruise ship that was attacked off the coast of Somalia by pirates recently. One of the passengers on the ship took a picture while they were firing rocket propelled grenades and machine guns at the ship. The ship used an LRAD - long range acoustic device that emits earsplitting noise in a specific direction to thwart the attack and prevent the pirates from boarding. By the way, there were two boats, this is just one of them:
