Today in Labor History November 6, 1971: The US Atomic Energy Commission conducted its largest ever underground hydrogen bomb test, code-named Cannikin, on the tectonically unstable Amchitka Island in the Aleutians. It had an explosive yield of almost 5 megatons of TNT. Greenpeace arose from the opposition movement against this test. By comparison, the largest ever nuclear test was Tsar Bomba (designed by Andrei Sakharov and others), at over 50 megatons, detonated on October 17, 1961. Its mushroom cloud was 8x the height of Mount Everest and its flare could be seen from 1,000 miles away.