The submarine is rapidly evolving, and the direction is decidedly robotic. While UAV (unmanned aerial vehicles) get all the press, there are also UUVs (unmanned underwater vehicles.) These have existed for several decades, mainly for use in finding and destroying high tech naval mines. Then again, one can classify torpedoes as UUVs, especially since over the last half century torpedoes have become a lot more intelligent and capable. Most modern torpedoes have computers and sensors on board, and can be unleashed to find and hunt down prey without outside assistance. Better battery technology, more powerful computers and mini-torpedoes are making it possible to build UUV submarines. Weighing only a few hundred tons, carrying smaller mini-torpedoes and capable to going out on missions lasting several days, or more, the UCUV (unmanned combat underwater vehicles) would be the quietest, fastest thinking and most lethal submarine available. It's enough to give the owners of manned subs nightmares, or worse.