Ro-68 was an Imperial Japanese Navy Type L submarine of the L4 subclass. First commissioned in 1925, she served in the waters of Japan prior to World War II. During World War II, she supported Japanese forces during the Battle of Wake Island and the invasion of Rabaul and took part in the Aleutian Islands campaign. She served as a training submarine from late 1942 to late 1944 before returning to a combat role in Japanese waters late in the war. She surrendered to the Allies in 1945 at the conclusion of the war and was scuttled in 1946.