Lada class, Russian designation Project 677 Lada is the new advanced class of diesel-electric attack submarine designed by the Russian Rubin Design Bureau. A program to develop a "fourth generation" diesel-electric submarine, it aimed to produce a highly improved version of the Project 636 with better acoustic signature, new combat systems and possibly air-independent propulsion. However, in 2019, Alexander Buzakov, the head of the Admiralty Shipyard, indicated that there were no plans to equip the Lada class with an air-independent propulsion system. In July 2022 it was reported that work on an electrochemical generator to produce hydrogen from diesel fuel and oxygen was continuing and that the Rubin Central Design Bureau signed a new contract in 2019 to continue work. This was scheduled to be completed by the mid-2020s. In 2023, the decision was taken to decommission and scrap the lead ship of the class, the Sankt Peterburg due to the very high costs of modernising the submarine.

The Kilo-class submarines are a group of diesel-electric attack submarines designed by the Rubin Design Bureau in the Soviet Union in the 1970s and built originally for the Soviet Navy.