I've never heard of this before : )
>From
>http://www.scmp.com/news/china/article/1580226/shanghai-san-francisco-100-minutes-chinese-supersonic-submarine
"China has moved a step closer to creating a supersonic submarine that
could travel from Shanghai to San Francisco in less than two hours. "
..
"However, during the cold war, the Soviet military developed a technology
called supercavitation, which involves enveloping a submerged vessel
inside an air bubble to avoid problems caused by water drag.
A Soviet supercavitation torpedo called Shakval was able to reach a
speed of 370km/h or more - much faster than any other conventional
torpedoes."
