Mars Bluff is an unincorporated community in Florence County, South Carolina, United States that bears the distinction of having been inadvertently bombed with a nuclear weapon by the United States Air Force.

Originally known as Marr's Bluff during the American Revolution, the area west of the Great Pee Dee River eventually became known as Mars Bluff at some point before the American Civil War.

While attempting to secure the weapon after a warning light went on in the cabin, the navigator mistakenly caused it to be released, and it crashed onto the bomb bay doors, opening them and continuing downward.

Although the bomb was not armed with its nuclear core (which was stored separately on the plane), it contained several tons of high explosives.

It landed approximately 50 yards from the house and garage of Walter Gregg.