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.

Impressive, but hideously expensive to operate, and they used liquid-fuelled missiles, which are not anywhere near ideal for submarines.

The Typhoons were elephants deployed to do a job which required only draught-horses.

They’re being paid off, and replaced with rather more sensible Borei-class subs, which carry solid-fuel missiles.