Pile of mud is a piece of scenery and an agility obstacle in the Underground Pass. It is used to climb up from the Spiked pit and in the northwest corner of the dungeon floor to climb up to a stone bridge and platform.
Climbing it to get out of the swamp area players enter when they attempt to step over Swamp get the message:
- "you climb up the mud pile
- it leads into darkness, the stench is almost unbearable
- you surface by the swamp, covered in muck"
Similarly, the Pile of mud is also used in the Plague City quest to exit the ardougne sewers.