SS Morro Castle was an American ocean liner that caught fire and ran aground on the morning of September 8, 1934, en route from Havana, Cuba, to New York City, United States, with the loss of 137 passengers and crew.

On the previous evening, Morro Castle's captain, Robert Willmott, had died suddenly, and his place was taken by Chief Officer William Warms as a strong northeast wind was developing under heavy cloud. At 2:50am, a fire was detected in a storage locker, which burned through electrical cables, engulfed the ship in flames and plunged it into darkness. Responses by the crew, the United States Coast Guard and rescue vessels were notably slow and inefficient, with lifeboats not loaded to their capacity. The decks were too hot to stand on, smoke made breathing difficult and passengers were forced to leap into ocean swells where swimming was impossible. By mid-afternoon Morro Castle was abandoned and the survivors were landed on the shores of New Jersey by an assortment of craft.

The cause of the fire was never established, though an overheated funnel and certain points of cabin design and electrical circuitry were noted. A theory of arson by a crew member has attracted support over the years, albeit without any concrete evidence. The high casualties are chiefly blamed on the crew's incompetent handling of the emergency.

On May 22, 1928, the United States Congress passed the Merchant Marine Act of 1928, creating a $250 million construction fund to be lent to American shipping companies to replace old and outdated ships with new ones. Each of these loans, which could subsidize as much as seventy-five percent of the cost of the ship, was to be paid back over twenty years at low interest rates.

One company that availed itself of this opportunity was the New York and Cuba Mail Steam Ship Company, better known as the Ward Line, which had been carrying passengers, cargo and mail to and from Cuba since the mid-19th century. Naval architects were hired by the Ward Line to design a pair of passenger liners to be named Morro Castle, after the stone fortress and lighthouse in Havana, and Oriente, after Cuba's Oriente Province.

At the Newport News Shipbuilding and Dry Dock Company, work was begun on Morro Castle in January 1929. In March 1930 the ship was christened, followed in May by her sister ship Oriente. Each ship was 508 feet (155 metres) long, measured 11,520 gross register tons (GRT) and had turbo-electric transmission, with General Electric twin turbo generators supplying current to propulsion motors on twin propeller shafts. Each ship was luxuriously finished to accommodate 489 passengers in first and tourist class and 240 officers and crew. In a growing age of passenger ships having cruiser sterns, Morro Castle and Oriente were built with classic counter sterns.

As built, Morro Castle was equipped with direction finding and submarine signalling equipment. Submarine signalling was becoming obsolete as a form of communication, so by 1934 it had been removed. That same year, echo sounding equipment and a gyrocompass had been installed on the ship.

Morro Castle began her maiden voyage on August 23, 1930. She lived up to expectations by completing the 1,100+ mile southbound trip in just under fifty-nine hours, and the return trip took only fifty-eight hours. Over the next four years, Morro Castle and Oriente performed as workhorses, rarely out of service and, despite the worsening of the Great Depression, able to maintain a steady clientele. Their success was in part due to Prohibition, as such trips provided a relatively affordable and (more importantly) legal means for customers to drink alcoholic beverages. The Ward Line's reasonable rates attracted Cuban and American businessmen and older couples, making the ships a microcosm of America during the period.