10. The Soviets lost about three dozen nuclear warheads in one incident
In October 1986, a Soviet Yankee I class nuclear submarine, powered by two nuclear reactors, was ripped by an explosion in one of the vessel’s 16 missile tubes. The explosion and resulting fire forced the submarine to surface, approximately 500 miles from the island of Bermuda. The Soviet submarine was being shadowed (as were all Soviet missile submarines while at sea) by an American fast attack submarine, USS Augusta. Rumors of a collision between the two submarines, which caused the leak which resulted in the explosion and fire, were denied by the commanders of both the Soviet vessel, K-219, and the American submarine. The Soviets successfully fought the casualty to the point that the vessel was able to surface, and rejecting help from the Americans standing by, was taken under tow by another Soviet vessel.
The tow was unsuccessful and the Soviets, in violation of their orders from Moscow, abandoned the submarine, though the Captain remained aboard in a last-ditch attempt to save his ship. Moscow ordered the crew back aboard, under the command of the Political Officer, but before the orders were carried out the submarine flooded beyond the point of no return, sinking to the bottom of the Atlantic in the Hatteras Abyssal Plain, settling at a depth of about 18,000 feet, more than three miles beneath the surface. It took with it to the bottom two nuclear reactors, which had been put in a safe condition, and more than three dozen nuclear weapons. Because the submarine was flooding internally in all of its compartments it was not crushed by the enormous pressure of the depths. In 1988 a Soviet hydrographic expedition examined the wreck, which was broken in two, with some missile silo hatches open, and the missiles and their nuclear warheads gone.