The Mark 15 hydrogen bomb, pictured above, is a thermonuclear bomb weighing a relatively light 7,600 pounds. It is roughly twelve feet long and three feet in diameter. Like most nuclear weapons, it can cause a great deal of destruction upon its detonation. Unlike most nuclear weapons, we managed to lose one.

On February 5, 1958, a B-47 bomber carrying a Mark 15 took off from Homestead Air Force Base near Florida’s southern tip. The B-47 was on a training run off the coast of Tybee Island, on the outskirts of Savannah, Georgia. But the mock mission went awry, as the bomber collided with an F-86 fighter jet also involved in the exercise. The F-86 was disabled and its pilot immediately ejected and survived. The B-47 was able to remain airborne, but was greatly damaged. Unable to guarantee a safe landing — a critical concern, given the plane’s payload — its pilot, Colonel Howard Richardson, proposed a solution: drop the bomb in the ocean.

And that is exactly what happened. Richardson, with permission from command, dropped the bomb from a distance of about 7,000 feet above sea level while traveling at over 200 miles per hour. The bomb landed in the ocean just off Tybee Island and, per Richardson, did not explode. The B-47 made an emergency landing at Hunter Army Air Field, and no one, miraculously, died. Richardson earned a medal for his cool-under-pressure performance in the skies.

But what ever happened to the bomb? No one knows. The day after the mid-air collision, Air Force and Naval recovery crews took to the seas to recover the jettisoned hydrogen bomb, but after a nine week search, they came back empty-handed. Another recovery effort was made in 2001, but it, too, was unsuccessful. More recently, in 2004, another Air Force colonel asserted that he has narrowed down the location to an area roughly the size of a football field, by triangulating off heightened levels of radioactivity in the area. But to date, the bomb still sits somewhere in the ocean, unrecovered.

This may be by design. The Air Force asserts that the bomb is safer there than it would be if jostled, as they assert, the weapon lacks a plutonium trigger, which is requisite to creating an explosion. However, prior testimony from W.J. Howard, an Assistant Secretary of State, suggested that this may be incorrect, and that the lost Mark 15 is, in Howard’s words, a “complete bomb.”

Bonus fact : A month after the above accident, the American military had another. On March 11, 1958, another B-47 bomber took off from Hunter Army Air Field (the same one at which the above-discussed B-47 made its emergency landing), bringing a nuclear weapon (in this case, a Mark 6 bomb) to the United Kingdom. While airborne, the plane signaled that the bomb was not properly secured, and the navigator went back to check. While doing so, he slipped and accidentally grabbed the emergency release cord, dropping the bomb into a rural part of Georgia. The bomb thankfully did not have any plutonium in it — the nuclear parts of the bomb were, effectively, packed separately — but it did have enough explosives to create a large mushroom cloud upon its landing and detonation. It left a 75 foot wide, 30 foot deep crater, and destroyed the home of a local resident. Apparently, no one died directly from the blast, but other reports suggest there was one related death.

From the Archives: Radioactive Red: Did you know that you may have a radioactive piece of dishware in your kitchen?

Related: Want some uranium of your very own? You can buy some on Amazon. Really. (But at the time of this writing, it is out of stock. But the reviews — 302 of them! — are hysterical.)