It’s fast, and very, very expensive ...

Submarines' top speeds are different when they're underwater than when they're cruising on the surface -- and not always in the same direction.

The Seawolf-class fast attack sub was deemed too expensive to mass produce in the wake of the ending of the Cold War and the fall of the Soviet Union.

It was once the fastest submarine on earth, but over the past four decades the USS Albacore has been transformed into a popular Seacoast attraction, offering a rare deep dive ...