The Cradles are large machines, built to permanently keep a single person alive within, that serve as access points to the Red Code. Each Cradle is a large sphere with several tubes protruding from it, the tubes likely being part of the self-sufficient life support system, and each has a different color. All of the cradles are protected by the tribes, although only Green's Cradle has a significant military presence around it, while the others are simply hidden underground, in the sea, or other mostly inaccessible places.
Four Cradles can be seen ingame: one in the Desert of Giants, one in the Clearing Below, one in the Sunken City, and one in the Tunnels. The Desert of Giants Cradle is the only one that can be accessed.
In the Polychromatic artbook, the dreamer within the 4th Cradle is referred to as the "Kvmot Bjy." This phrase is encrypted with a ceasar cipher with a left shift of 5, just as Mr. Kiepchen's dialogue is, and when decoded becomes "Party God."