1. Type VII U-Boat

Perhaps the ultimate symbol of the deadly underwater predator, the Type VII U-boat may be the most famous submarine class in history. It was also the most numerous, serving as the workhorse of the German submarine forces in World War II. At around 900 tons displacement, and armed with five torpedo tubes, the Type VII was smaller than the big American fleet boats, but it came perilously close to winning the Battle of the Atlantic. But the cost was frightful; of 1,100 U-boats constructed in World War II - including 700 Type VII's - more than 800 were lost. More than 75 percent of U-boat crewmen perished.