The First Soviet Nuclear Submarines
The specifications laid out would focus on a submarine that was capable of out diving and out running surface ships and other submarines.
As a result of this, the design specification was for a submarine to be built using high tensile steel known as AK-25 as well as, two nuclear reactors but also having a hydrodynamic hull form, thus the project 627 unlike Nautilus has a cylindrical cigar shape hull form with a hydrodynamic swept back sail and a streamlined stern fin giving the 627 an edge in speed and diving depth.
Being a cigar shape the submarine is technically more hydrodynamic hence the ability to obtain 30 knots, but there is another reality to this she could also dive much deeper than other boats and the 627’s have been as deep as 340 meters, 140 meters deeper than Nautilus.
The 627’s also possessed a double hull, with the pressure hull being split into nine watertight compartments, the submarine also had a high reserve buoyancy (31% in comparison to Nautilus 16%) to ensure survivability should the boat be attacked or run aground.