This would be pretty revolutionary if it can be successfully applied to real submarines:
Scientists at the University of Illinois in the United States have developed and successfully demonstrated a sonic cloak that could make submarines completely invisible to sonar.
Whoa. That appears to apply to active and passive means of detecting submarines based on sound.
That doesn't mean that there aren't other means that could be used that don't rely on sound. It wouldn't affect devices that could detect the uplifting of water that a submarine displaces, for example. But I didn't think that was more than a theoretical weakness of subs.
If submarines can truly be made invisible to sound detection systems, how can anything that floats on the surface survive?