The USS S-42 was a United States Navy submarine, part of the S-class fleet. Launched on March 1, 1924, it was designed for coastal defense and reconnaissance missions. The submarine was 219 feet long and had a surface displacement of around 850 tons. Commissioned on December 15, 1925, the USS S-42 served primarily in the Pacific Ocean. It was decommissioned in 1931 and later sold for scrap in 1945. The S-class submarines, including the S-42, played a crucial role in the development of submarine technology during the interwar period.