Star Trek

I recently read an article about US Navy torpedoes, which remind me of Star Trek torpedoes.  One proposes to vaporize water at the tip of the torpedo, from its high speed. This produces a pocket, in which the weapon "flies"  underwater. Traveling in this vapor pocket dramatically reduces the drag. It can also be reconfigured to hunt other submarines and even to intercept other torpedoes. Its "supercavitation" turns this torpedo into an underwater missile, capable of reaching its target before the threat can respond.

http://www.navy.mil/navydata/cno/n87/usw/issue_14/torpedoes.html

I would think that the Navy should invest in a system similar to how an octopus moves. Basically the octopus takes in water and then forces the water out through vents at a high velocity to create the foreward motion.