The Pools of Flame and Tears
Cardinal directions have no meaning in the Pools, and thus the people use a different set of directions: waterway, fireway, knuckles, and palm.
For reasons unbeknownst to the average citizen, the Pools of Tears are in the opposite direction from the Pools of Flame. Each direction provides a boundary – as you go too far fireway, you are overcome by massive pools of flowing lava, and as you go too far waterway, the caves end in pools of saltwater and rock. Therefore waterway means “towards the Pools of Tears” and fireway means “towards the Pools of Flame”.
In the caves there is a limited amount of a third dimension, with some caves at higher altitudes than others. These differences are described with the standard “up” and “down”, leaving two directions unaccounted for. People describe the axis perpendicular to the fireway and waterway axis with the outstretched, open hand, held parallel to the ground.
The outstretched fingers represent waterway and the wrist represents fireway. The thumb denotes the direction. If the hand is held palm down, the direction represented is called knuckles. If the hand is held palm up, the direction represented is called palm.