Knowledge, The planes

(the Inner Planes, the Outer Planes, the Astral Plane, the Ethereal Plane, outsiders, elementals, magic related to the planes)

This material is Open Game Content, and is licensed for public use under the terms of the Open Game License v1.0a.

Synergy

If you have 5 or more ranks in Knowledge (the planes), you get a +2 bonus on Survival checks made while on other planes.