USS Cyclops
USS Cyclops was one of the largest ships in the U.S. Navy, a collier about 540 feet long built to haul coal for the fleet. In early 1918, during World War I, she sailed from Brazil carrying roughly 10,000 to 11,000 tons of manganese ore, a metal crucial to steelmaking. She stopped at Barbados, partly because she was overloaded, and left on March 4 bound for Baltimore with 306 people aboard.
She never arrived. No distress call was ever received, and no wreckage, lifeboat or body was ever found. The Navy has called it one of the most baffling mysteries in its history, and it remains the largest loss of life in U.S. naval history not directly involving combat.
There were problems before she sailed. One of her engines was reported to be damaged, her commanding officer, George Worley, had clashed with his crew, and there were rumors of unrest aboard. A German submarine or raider was suspected at first, but wartime records later made that look unlikely. Many now suspect structural failure, perhaps worsened by corrosion or a heavy sea pounding a ship riding low under dense ore. One descendant of a crewman who has studied the case points to the deep Puerto Rico Trench. Without a wreck, none of it can be confirmed.
Verdict: UnsolvedNo wreckage or distress call was ever found; structural failure or a storm is likely but unproven.