Akula ( - Shark) was a submarine built for the Imperial Russian Navy. The boat was designed by Ivan Bubnov and was an amalgam of the previous Minoga and the Kasatka class submarine designs. The design was presented to the Marine technical committee in late 1905. Initially the boat was to use petrol engines but these were replaced by safer diesels. The boat's design was a single hull/ saddle tank type with a diving depth of 25 fathoms (45 m). Significant initial problems were experienced and the electric motor and propellers which needed to be replaced. Akula was the first Russian submarine able to cruise long distances. In 1912 Akula made the world's first multi-torpedo volley with five torpedoes.