The USS O-4 was a submarine of the United States Navy, part of the O-class submarines built during World War I. Launched in 1918, it was designed for coastal defense and had a displacement of about 1,000 tons when submerged. The submarine was equipped with torpedoes and had a crew of around 30 men. After serving in the Navy, the USS O-4 was decommissioned in 1924 and later sold for scrap in 1931. Its design and capabilities contributed to the development of future submarines, influencing naval warfare strategies during the interwar period and beyond.