Castle Bravo Nuclear Test, Marshall Islands (1954)

The United States' largest thermonuclear detonation at Bikini Atoll yielded 15 megatons — 2.5 times the predicted yield — showering the crew of the Japanese fishing vessel Daigo Fukuryū Maru and Marshall Islanders with lethal radioactive fallout, causing international outrage and galvanizing the global nuclear disarmament movement.