Maps, directions and navigation on the Discworld are fundamentally different from the more common spheroidal planets, in that there are no poles and any system of rectangular co-ordinates would eventually cause you to sail off the edge. Directions are given by polar co-ordinates indicating "inward", "outward", and "around", with or against the rotation of the disc. "Inward" is toward the Hub, or hubwards. The other directions (q.v.) are Rimwards, Turnwise and Widdershins.