The official cause of the Sultana disaster was determined to be mismanagement of water levels in the boiler, exacerbated by "careening". The Sultana was severely overcrowded and top heavy. As the steamship made its way north following the twists and turns of the river, the Sultana listed severely to one side then the other. The Sultana's four boilers were interconnected and mounted side-by-side, so that if the ship tipped sideways, water would tend to run out of the highest boiler. With the fires still going against the empty boiler, this created hot spots. When the ship tipped the other way, water rushing back into the empty boiler would hit the hot spots and flash instantly to steam, creating a sudden surge in pressure. This effect of careening could have been minimized by maintaining high water levels in the boilers. The official inquiry found that Sultana 's boilers exploded due to the combined effects of careening, low water level, and a faulty repair to a leaky boiler made a few days earlier.
In 1888, a St. Louis resident named William Streetor claimed that his former business partner, Robert Louden, made a deathbed confession of having sabotaged the Sultana by a coal torpedo. Louden was a former Confederate agent and saboteur who operated in and around St. Louis. Louden had the opportunity and motive to attack the Sultana. He may have had access to the means. (Thomas Edgeworth Courtenay, the inventor of the coal torpedo, was a former resident of St. Louis and was involved in similar acts of sabotage against Union shipping interests.) Supporting Louden's claim are eyewitness reports that a piece of artillery shell was observed in the wreckage. Louden's claim is controversial, however, and most scholars support the official explanation.