Navigating Underground
Getting from place to place in the Murk is much harder than it is in the surface world. There are no sun, moon, or stars to guide oneself, just endless darkness and fields of rubble. Even darkvision, with a range of 60 feet, helps only a bit.
Each square represents one hour of travel. For every square traveled, have a player roll a WISDOM (Survival) check by rolling a d20 and adding either their WISDOM or Survival bonus (whichever is higher) and consult the table. Give the player Advantage if they have a navigational strategy, following a river or a cobblestone path, or if multiple characters are helping.
5 or lower: they exit the square heading in the wrong direction
6 - 11: they stay stuck in the same square (moving in circles)
12 - 16: they exit the square as normal
17 or higher: they move two squares in their desired direction