The torpedo can swim after potential terrorist or enemy soldiers trying to get into coast bases or near ships. For now, it's not lethal: It will only track its target, slowing down when it is near and then circling its objective sending its exact position using GPS.
Jim Pollock—project manager for the Integrated Swimmer Defense Program at the Naval Undersea Warfare Center—says that the Moray Eel torpedo is just "a candidate technology for a solution to deterring swimmers. It's not necessarily a solution that the Navy has picked at this point."
Defense Tech, however, speculates that while this may become a water surveillance drone, it may only be a matter of time before it is armed to kill. I'm sure the military are not thinking about that at all. [Defense Tech]