Hiadonu is a swamp in the western tracts of Gakebe. It has been expanded over a thousand years by canals and digging. Initially, this was done for defensive measures, forming a natural defensive barrier versus whatever came down from the north. The extension of the swamp northwards formed an unbroken natural defense starting with Hoze Huemutril then linking with Hiadonu, Dianu, and then buttressed against the jagged spires of Qibemjues. The extension of the swamp had lasting effect which closed the last easy route for invaders entering Kalaran from Padimza.

In the Second Epoch, cultivation and farming extended into the man-made parts of the swamp. This led to villages and a few towns being built in the swamp. All the Shou living areas are built above the waters on stilts, rocks, and a few held aloft with magic. The others of the swamp are the deep ponds and lakes near the center. These submerged places are the abode of Viidostor and a type of Pyrmidian Ghoul that is aquatic. The presence of these creatures in the area has led to some thinking that a Pyramid of Power may lie submerged in the swamp.

The swamp is dotted with outposts and fortresses, some in-use by the Shounejo or abandoned to nature and beasts. Many of these places were built as the swamp was being expanded. They served as a place of refuge for workers when under threat by marauders or large scale Tiya'lith attacks.