A Super-Fast Submarine

I always knew something was gonna come along to replace the modern submarine, something like the UUVs now being deployed. This may be the answer from UPI:

The Defense Advanced Research Projects Agency is looking for a really fast, really small submarine.
It's also seeking a major breakthrough in physics: making supercavitation actually work on a large scale.
Supercavitation refers to a process of displacing water around a submerged vessel so that it travels in a gaseous or vaporous cavity. Theoretically, that can be done either by propelling a blunt-nosed vessel at a very high speed -- its nose forces the water out of the way -- or by injecting gas into a partially developed cavity, according to DARPA.

DARPA envisions an eight-foot diameter craft that would carry a small unit -- presumably Navy SEALS -- or high-value cargo quickly through coastal waters.