According to Bellona, the “Dmitry Donskoy” features a “multi-hulled design, having two parallel main hulls, also called strong hulls, inside the light hull. Maximum diving depth is 400 m.” Video after the break.
..the submarine was under upgrade works since 1989 and was equipped with the modern systems of communication, acoustic and radiation control. Speed is 12 knots when surfaced and 27 knots when submerged. Typhoon is capable of spending 120 days at sea. The submarine is divided into 19 compartments and powered with two 190 megawatts nuclear reactors