Don't know if its been mentioned here, but 30 or so years ago, a US nuclear carrier was being shadowed by a Soviet Alfa class sub. The US skipper decided to show the Alfa some "tricks" and opened up his speed; the Alfa kept up, so he increased his speed; again the Alfa kept up; again the US carrier increased speed to a "very high level" (according to reports). The Alfa then just opened up his throttle and left the carrier in his wake, causing much consternation in US Navy circles. I heard this from a neighbor when I was living in Virginia Beach (he was a nuclear carrier skipper).
Here's a story on the Alfa class Soviet sub:
http://foxtrotalpha.jalopnik.com/russias-alfa-class-was-the-terrifying-hot-rod-sub-of-th-1637540064
