The Spine is a collection of small islands bridging the gaps between several larger islands. They're easy to navigate, even with small row boats and canoes.

The western half of the Spine is Courier territory, including The Sisters.

The eastern half of the Spine is Pirate territory, including Skull Atoll, Brimstone Island and Ribcage.

There's a pair of research outposts setup on the two Spine segments nearest to Necropolis.