The GSS New Castle is a New Castle-class nuclear-powered attack submarine. It's design is based off that of USS Dallas, a Los Angeles-class submarine for the U.S. Navy.

Although its design is based off of the Dallas, the New Castle is much bigger, faster, and more capable than an Ohio; since it is meant to keep up with the U.S.'s own Virginia-class submarines.

Six of the New Castle's, included the self-named flagship, are--despite the U.S.'s policy of non-poliferation-- "Boomers". Every boat carries 64 missiles. For these six boats, 13 of which are ICBMs; each carrying a 20 megaton warhead.

These boats, when surfaced or docked, fly two flags (the Global Naval Force flag and the United States flag), one on each side of the crow's nest, to designate that they are a part of the Nuclear Triad System employed by U.S. Strategic Command, of which these boats are commanded by, and are only called upon when as a last resort.

The other 51 missiles are long-range Tomahawks and some are a part of the boat's anti-missile defense system.

The NC's are fleet footed, clocking in at about 45 knots at max depth of 100,000 feet, and 80 knots on the surface.

In combination with the Pennsylvania-class battleships, Assurance-class destroyers, and Donigan-class carriers, these subs enable the Global Naval Force to achieve complete supremacy in any and all battles at sea. That includes rogue Atlantean States.