Wakamiya was initially the Russian freighter Lethington, built by Duncan in Port Glasgow, United Kingdom, laid down in 1900 and launched 21 September 1900. She was captured on a voyage from Cardiff to Vladivostok during the Russo-Japanese War near Okinoshima in 1905 by the Japanese torpedo boatTB No. 72. She was acquired by the Japanese government, renamed Takasaki-Maru until given the official name of Wakamiya-Maru on 1 September, and from 1907 was managed as a transport ship by NYK. In 1913 she was transferred to the Imperial Japanese Navy and converted to a seaplane carrier, being completed on 17 August 1914. She was a 7,720-ton ship, with a complement of 234. She had two seaplanes on deck and two in reserve. They could be lowered onto the water with a crane, whence they would take off, and then be retrieved from the water once their mission was completed.
From 5 September 1914, Wakamiya conducted the world's first naval-launched air raids during the first months of the First World War from Kiaochow Bay off Tsingtao, which is located in China. On 6 September 1914 a Farman aircraft launched by Wakamiya attacked the Austro-Hungarian cruiser Kaiserin Elisabeth and the German gunboat Jaguar in Qiaozhou Bay; neither ship was hit. Her seaplanes bombarded German-held land targets in the Tsingtao peninsula of Shandong province and ships in Qiaozhou Bay from September to 6 November 1914, during the Siege of Tsingtao. British officers serving in the Battle of Tsingtao commented on the operations of the Wakamiya: On 30 September, Wakamiya struck a German mine and had to be repaired for a week. On this occasion, her seaplanes were transferred on land at Shazikou, from where they accomplished further scouting and attack missions: Altogether the seaplanes made 49 attacks, dropping 190 bombs on German defenses until the German surrender on 7 November. According to the British Naval Attaché to Tokyo, Captain Hon. Hubert Brand, who had been stationed for three months on Imperial Japanese Navy warships throughout the battle, the bombs used by the seaplanes were about equivalent to 12 pdr. shells.
Later developments
Wakamiya was modified as a regular aircraft carrier with a launch platform on the foredeck in April 1920. She accomplished in June 1920 the first Japanese take-off from an aircraft carrier. It is thought she had a pioneering role in developing aircraft carrier techniques for the Japanese aircraft carrier Hosho, the first purpose-built aircraft carrier in the world. She was used as a trials ship after 1924, stricken 1 April 1931, and scrapped in 1932.