Sci-fi related questions about submarines.

[EFileTahi-A]

Ok. Lets summarize the key info:

For weapons we have:
- Sonic Pulse (Directional sound waves which can compact water above the enemy. Most useful if the enemy ship is stationary)
- Plasma / Photon torpedoes that travel in water through supercavitation.
- Conventional torpedoes (with devastating power but limited payload).

For defense we have:
- Magnetic Shield
- Short Defense Laser (to pop incoming torpedoes)

What about a sort of weapon that could froze water at a certain location so it could block incoming torpedoes? Maybe this could actually be explored and turned into a defense shield?