PALOMARES, SPAIN 1966
UPDATE 2011: After 45 years, the U.S. Government is condidering may possibly thinking about cleaning up the contaminated areas. In February, Foreign Minister Trinidad Jiménez, announced to Spanish Senate that clearing Palomares was "a priority." He didn't say it was a High Priority, we should see progrss this century. See incident report below:
On January 17, 1966, a B52 bomber collided with KC-135 tanker aircraft off the southeast coast of Spain at 29,000 ft. They exploded in a fireball over Palomares. There were four hydrogen bombs in the hold of the B-52. One landed in tomato fields and was recovered. In two others, the conventional explosives in the device detonated, scattering plutonium dust around the impact site. At the time, 1,590 tons of contaminated material were excavated and sent for disposal at the Savannah River Plant in South Carolina. However, a 2004 study showed significant contamination still present in the area, with unusually high levels of radiation were detected in snails and other lifeforms in the area.

The Spanish government was forced to take over some of the affected property - especially plots committed to agriculture or development. Beginning in 2006, the U.S. and Spanish government began a study to determine how much plutonium leaching has taken place in the area - now a tourist destination - since 1966. In April 2008, CIEMAT announced they had found two trenches, totalling 2,000 cubic meters volume, where the U.S. Army had stored 2000 cubic meters of contaminated earth during the sixties, and apparently forgotten about it. The site had been slated for hotels and golf courses. The U.S. taxpayer will be paying a couple of million more to dig out some more nuke contaminated dirt.
TWO SUBS SUNK WITH NUKES ON BOARD: STILL DOWN THERE SOMEWHERE
The USS Scorpion sank about two miles deep in the Atlantic about 300 miles south of the Azores Islands. It was carrying two nuclear warheads with the Kremlin written across the nosecone. The depth of the water has prevented recovery of both the reactor and the weapons. Another couple of decades later, a Russian nuclear submarine, the Komsomolez, sank to a depth of 5500 feet in the North Atlantic, taking with it two nuclear warheads.
STILL MISSING ONE NEAR SAVANNAH, GA
On Feb. 5, 1958, bomber pilot Howard Richardson had to jettison the hydrogen bomb he was carrying after colliding with a fighter jet. The bomb disappeared in the shallow waters of Wassaw Sound, about 12 miles from Savannah, Georgia, a city of 100,000 people. The bomb has never been found.
The Air Force has said the bomb contains uranium and about 400 pounds of conventional explosives, though it lacks the plutonium capsule needed to trigger a nuclear blast. The amount of uranium was undisclosed.