This is a sand-style zone similar to Sandworm Lair.
The first two levels of this zone are normal sand caverns connected by clear paths.
On the third level, the sand caverns are no longer connected by open paths, and the player must dig through the sand walls with the Stralite Sand Shredder quest item in order to find the entrance to the next level. The Shredder is automatically activated whenever the player tries to move into a sand wall, and will immediately dig out the 8 tiles surrounding the player, as well as the tile the player is standing on. It takes 20 turns for a dug out sand tile to collapse back into a wall.
Having some means of remote scouting (e.g. a wand of clairvoyance) can help players locate the open rooms on this level, and choose a good angle to breach into them so as not to be overwhelmed by a swarm of enemies. With some preparation, it is also possible to lure large groups of enemies into collapsing sand tiles and let them be crushed and suffocated to death.
The final level (10x130 tiles) requires the player to tunnel steadily northward to get to the quest location.