Submarines reign supreme in the undersea world. Trace the evolution of submarines from the hand-cranked submersibles of the Civil War to the nuclear-powered warships prowling the oceans today.

Submarines reign supreme in the undersea world. Trace the evolution of submarines from the hand-cranked submersibles of the Civil War to the nuclear-powered warships prowling the oceans today.

The word conjures images of majestic Spanish treasure ships, hulls bursting with gold and plunder. But galleons were also fast fighting ships and workhorses of the Age of Discovery.

Called "the greyhounds of the sea," clippers were the fastest wind-powered ships ever. Traveling over 2,000 miles within a week, the 19th-century clippers brought the world back to American shores.

The small wooden Patrol Torpedo Boats of WWII were among the most powerful warships of all time. PT vets recall why their speed and maneuverability were too much for giant, steel-hulled targets.

For the most exclusive travelers, ocean liners offered opulence to rival the world's richest hotels. Rare footage offers an insider's view of the great transatlantic liners of the 1920s and '30s.