Laid down as SS Marine Hawk, she was transferred from the Maritime Commission for conversion to a hospital ship, and served in that capacity through the end of the war.

Haven participated in the Korean War and eventually ended her military career acting as a floating hospital in Long Beach, California.

Initially named SS Marine Hawk, Haven was launched under Maritime Commission contract by Sun Shipbuilding & Drydock Co., Chester, Pennsylvania, on June 24, 1944.

She arrived off the destroyed Japanese city on September 11, 1945, and brought on board a group of allied ex-prisoners of war, some of them suffering from the effects of the atomic blast.

During the remainder of 1945 the ship was engaged in transporting patients from Guam, Saipan, and Pearl Harbor to San Francisco, arriving after her second long voyage on January 31, 1946.

At San Francisco, the USS Haven took on radiological equipment and scientific researchers in preparation for the forthcoming atomic tests in the Pacific, Operation Crossroads.

Haven departed 10 October for Pearl Harbor and the United States, and upon her arrival and decontamination was assigned once again to transport troops from the Pacific outposts to California as AH-12.

[1] Haven sailed again for the United States 16 September 1952, and, after the installation of a new flight deck to facilitate helicopter evacuation of patients, once more steamed out of San Diego 24 January 1953.

Haven sailed to Oran and Marseille in October to disembark the soldiers, and completing her round-the-world voyage arrived at Long Beach via the Panama Canal 1 November 1954.