"The Lada-class submarines are designed to defend coastlines against ships and other submarines, gather intelligence, provide surveillance and reconnaissance missions, and act as a mother ship for special forces. With its new air-independent propulsion plant, a Lada submarine can remain submerged for as many as 25 days. With its vast array of weapon systems, the Lada is also world’s first non-nuclear submarine to be equipped with specialized launchers for cruise missiles."
http://sputniknews.com/russia/20160102/1032604320/russia-submarine-stealth.html