#2. Russia (Soviet Union)

Number of Tests: 715

The Soviet Union has the distinction of detonating the largest bomb ever created. It was dropped on October 30, 1961 in the Arctic Cricle. Known as "Tsar Bomba," the fusion device yielded a destructive force of 50 megatons, equivalent to ten times the combined power of all of the explosives used in World War II. The resulting mushroom cloud plumed 38 miles into the sky, and it swept around the planet three times before its dust particles finally settled.

The world will hopefully never see anything like Tsar Bomba ever again.

Sources: Yang et. al. & Union University

(Image: Wikimedia Commons)