It was a little early to be swimming in the Mediterranean that year. But in early March 1966, Manuel Fraga Iribarne, the Spanish information minister at the time, and Biddle Duke, the American ambassador in Madrid, together with their respective families, plunged into the chilly waters off the Costa Cálida. Journalists from around the world had gathered on the beach of the small village of Palomares to report on the two families' spring bathing outing. Their interest would have been surprising, if it hadn't been for the hydrogen bomb lying on the ocean floor only a few kilometers away, a bomb with more than 1,000 times the explosive force of the one that flattened Hiroshima.
Only a few weeks earlier, on Jan. 17, 1966, the worst nuclear weapons incident of the entire Cold War had taken place off Spain's southeastern coast. During an aerial tanking maneuver, an American B-52 bomber and a KC-135 tanking aircraft collided in mid-air at 9,000 meters (29,000 feet), and both planes exploded in a giant fireball over Palomares. There were four hydrogen bombs in the hold of the B-52. One landed, unharmed, in tomato fields near the village. The non-nuclear fuse detonated in two others causing bomb fragments and plutonium dust to rain down on the impact site. The fourth bomb fell into the water somewhere off the coast, burying itself in several meters of silt. But where exactly did it fall?