Russian submarine Delfin

Delfin (Russian: Дельфин, lit. 'dolphin') was the first combat-capable Russian submarine. It was laid down in July 1901 by the Baltic Works in Saint Petersburg, added to the Imperial Russian Navy list in September 1902, and launched in May 1903 before beginning sea trials in the Gulf of Finland in June 1903. The trials were finished in October of that year and the submarine entered service, initially designated as a torpedo boat. During its construction it was initially named No. 113, which was later changed to No. 150, before finally receiving the name Delfin on 13 June 1904. The submarine's armament included two Drzewiecki drop collars on the outside of the submarine, each holding one torpedo, and a single machine gun.

It was first used as a training boat for new submariners as the Russian Navy decided to expand its submarine fleet and started preparing their crews before new vessels were completed. Despite being considered a success Delfin suffered two serious accidents early on in its career, a sinking in June 1904 and a large explosion in May 1905, with loss of life among the crew in both cases. Delfin was sent to the Pacific during the Russo-Japanese War and patrolled the coastal area near Vladivostok in the first half of 1905 to deter Japanese attacks. After the war it was used as a training boat for officers and crew and remained in the Russian Far East until the spring of 1916.

The final assignment of the submarine was serving in the role of coastal defense off Kola Bay after being transferred to the Arctic Ocean Flotilla. It was damaged in a storm and eventually struck from the navy list in August 1917. Delfin was scrapped in 1932.