Spiny Norman said:

A Soviet/Russian Typhoon-class nuclear submarine, the largest subs ever made. Inside the outer hull are two large, long tubes that contain the living spaces, etc. I think the missiles are situated outboard of those tubes but still inside the outer hull.

“The Soviet Typhoon-class nuclear-powered ballistic missile submarines are the largest ever built, displacing 48,000 tonnes submerged. Measuring 175m long and 23m wide, they utilized a unique triple-hull design to ensure survivability under Arctic ice. They were designed for long, silent patrols, featuring amenities such as a gym, sauna, and small pool for the crew.”