China claims it has found a way to create a supersonic underwater vessel that could travel from China to San Francisco in less than two hours using new developments in supercavitation. This could be extremely useful for travel -- but also for the development of underwater weapons. In fact, this is a military project.
This technique was originally developed for Shakval, a torpedo capable of reaching 370 km/h developed by the Soviet Navy during the Cold War. The size of the bubble and the speed was limited.
Now this new Chinese research claims they have found a way to generate a much bigger air bubble, drastically reducing friction of large underwater vessels. They say they would be able to create a full-size supercavitating submarine capable of reaching the speed of sound underwater -- about 5800km/h. That or a sneaky, big arse supersonic nuclear missile, of course.