Typhoon-class submarines feature multiple pressure hulls that simplify internal design while making the vessel much wider than a normal submarine. In the main body of the sub, two long pressure hulls lie parallel with a third, smaller pressure hull above them (which protrudes just below the sail), and two other pressure hulls for torpedoes and steering gear. This also greatly increases their survivability – even if one pressure hull is breached, the crew members in the other are safe and there is less potential for flooding.