On March 19, 1906, by the decree of Emperor Nicholas II, the Russian submarine fleet was established. A new class of combat ships, submarines, was added to the military fleet. The fleet included 20 submarines "Forel", as well as submarines of the types "Kasatka", "Som", and "Osёtr", which had been built by that time. The Naval Minister Alexei Alexeevich Birilev received instructions from the Emperor to include submarines in the classification of the ship composition. On April 9 of the same year, a Training Submarine Division was established at the port of Emperor Alexander III in Libava. On January 26, 1909, the Emperor approved a badge for graduates of the Submarine Officer Class.

The technologies of the era of Nicholas II were significantly ahead of their time. In 1915, a submarine equipped with 12 torpedo tubes, large-caliber machine guns, and two artillery installations was built. The ships created in Russia under Nicholas II participated in World War II, becoming the striking force of the Soviet fleet, simply renamed in a "revolutionary manner". The most mass-produced serial type became the boats of the "Bars" series. One such boat served in the fleet under both Lenin and Stalin, participated in two world wars, and was decommissioned only in 1955, already in the nuclear age. The rescue vessel "Volkhov", built under the guidance of Colonel A.P. Shershov, became one of the most advanced in the world in its class. It still serves in the Black Sea Fleet of the Russian Federation and remains relevant in modern conditions.

Since 1906, a new holiday has appeared in the Russian Empire, Submariner's Day.