Plasma Gases and Its Affects on underwater travel

   DARPA’s Underwater Express Program has a characteristically brief description. It is intended to: ”...demonstrate stable and controllable high-speed underwater transport through supercavitation. The intent is to determine the feasibility for supercavitation technology to enable a new class of high-speed underwater craft for future littoral missions that could involve the transport of high-value cargo and/or small units of personnel. The program will investigate and resolve critical technological issues associated with the physics of supercavitation and will culminate in a credible demonstration at a significant scale to prove that a supercavitating underwater craft is controllable at speeds up to 100 knots.”
                    Supercavitation is the use of cavitation effects to create a large bubble of gas inside a liquid. The cavity (the bubble) reduces the drag on the object, since drag is normally about 1,000 times greater in liquid water than in a gas. Current applications are mainly limited to very fast torpedoes.

         DARPA to begin testing ultra-fast mini-sub...

Turning science fiction in fact once again, DARPA, is ready to begin testing phase of a new ultra-fast mini submarine, capable of traveling at 100 knots.
In the United States the primary DARPA contracts for the "100-knot submarine" have been awarded to General Dynamics/Electric Boat, Northrop Grumman, New Systems Tech, and the University of Pennsylvania 's Applied Physics Laboratory.
       DARPA calls this program underwater express.  

Underwater Express

The goal of the Underwater Express program is to explore the application of supercavitation technology to underwater vehicles, enabling high-speed transport of personnel and/or supplies. Supercavitation places the vehicle inside a cavity where vapor replaces water, reducing both the drag due to fluid viscosity by orders-of-magnitude and power requirements dramatically. This program will use modeling, simulation, experiments and testing to understand the physical phenomena associated with supercavitation and its application to underwater vehicles.