A tanker carrying a load of molten sulphur, the SS Marine Sulphur Queen, disappeared off the southern coast of Florida in February 1963. As a result, the wreckage and 39-member crew were lost without a trace. According to the U.S. Coast Guard's investigation, the ship was in questionable condition and probably wasn't seaworthy to start: Fires were commonplace and the ship was known to have a "weak back," meaning that the keel was likely to split when weakened by corrosion. When the ship was converted from its original purpose as an oil tanker to carry molten sulphur, a high center of gravity resulted that might have caused the vessel to capsize. No one knows for certain what happened to the Sulphur Queen, but its demise was probably a result of its poor condition rather than a mysterious force.