"I have nearly all of my magic still," Nethezar comments as he waits for Kushnak to ferry him across.
Without incident, Kushnak carries the others across, and in short order they start down the hallway.
Unlike the rest of the complex, this hall is not light with the pale blue light of the everburning torches, to which you'd become accustomed. After about 50 feet, near the distance where, for Nethezar at least, the light of the prior room is nearing uselessness, the hall abruptly changes. Instead of the square walls and floor, you see an intersection where the floor is roughly flat, but the walls and ceiling are actually made of the top three-quarters of a circle. The floor also drops at the intersection, with paths going forward and to both sides, and is covered in a layer of water.
"Is that... the Free City's sewer system?" Nethezar opines.
In short, that is precisely what it looks like.