Delfin () 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.
Background
thumb|left|Delfin schematics
In the 19th century the Imperial Russian Navy had been among the European navies that took interest in developing submarines and several experimental underwater craft were built by Russia during that time, with the earliest dating back to the reign of Peter the Great. Although not all of these projects were successful, they allowed the Russian Navy to get an understanding of submarine design and construction. The interest in submarine development continued by the turn of the century, and on 19 December 1900 a submarine committee was founded within the Naval Technological Committee (MTK), led by the engineer Ivan Bubnov, who would be responsible for the design of most tsarist submarines up until the Russian Revolution of 1917. The other members of the organization were engineer Ivan Goryunov and the officer Mikhail Beklemishev. The submarine committee was tasked with studying foreign designs as preparation for designing and constructing a combat submarine for the Russian Navy.
Design and construction
On 16 June 1901 the Russian submarine designers led by Ivan Bubnov presented a proposal to the Naval Technological Committee which was a version of John P. Holland boats with modifications made by Bubnov. This design would become the Delfin. Bubnov's changes included changing the position of the ballast tanks and replacing internal torpedo tubes with Drzewiecki drop collars which held torpedoes on the outside of the boat. The proposal was quickly approved and the submarine, designated as torpedo boat No. 113, was laid down on 5 July 1901 at the Baltic Works in Saint Petersburg. It was labeled a torpedo boat by the Russian Navy because there were no commissioned submarines in the fleet up to this point.