The perilous Shifting Mires existed within Lurch Canyon on Pasaana. This region was characterized by expanses of treacherous terrain; specifically, black sand that was unstable and capable of engulfing almost anything that became trapped within it. Underneath the Shifting Mires lay extensive tunnel networks crafted by the vexis, which also served as a habitat for indigenous gouge-beetles.
Numerous individuals met their end in the sinking terrain, frequently being consumed and dying due to the hazardous creatures or the absence of food and water. At some point following the Battle of Endor, Ochi, a Sith loyalist, perished from reasons not fully known within the tunnels, having fallen into the Shifting Mires along with his speeder and dagger.
In 35 ABY, a contingent of Resistance members, including Rey, Chewbacca, Finn, Poe Dameron, C-3PO, and BB-8, were ensnared by the sinking fields, leading them to the subterranean caverns. They successfully recovered the dagger and encountered an injured vexis serpent. Rey utilized the Force healed ability on the creature, which then granted the group safe passage.