The Nautilus is similar to the Dreadnought and is a high-speed super submarine in mission B-alpha.
While underwater it attacks with powerful torpedos and missiles. When on the surface, it attacks with a more powerful 50.8 cm naval gun and the first of sci-fi Laser weapons.
This super submarine has an underwater health bar that must be depleted to force it to the surface, and then another health bar on the surface
Note:
The survival campaign does not have alpha or beta missions so this super sub will not appear in that campaign
Nautilus stats in game
The Nautilus surfacing from the deep
The Nautilus In battle