Elsine, Ronin and Ikky continued down the tunnel, while they were going down Ikky was making notches in flat areas that would have to be modified to give the sewer the slope it needed, he also marked the small side tunnels and hollows through which a human could not fit but those damn centipedes could, but not before making sure to kill with fire or any other magic all those bugs that were hiding in the shadows.
They continued down and mapping that network of caverns, at one point the tunnel they were following began to fill with water, the three of them began to fly over that spring water and leaks without wasting time, if the sewer had its own self-cleaning system all the better.
Finally after descending many levels and making many turns, and passing through many narrowings that the magic of the three players was enlarging and securing as they passed, the sound of a waterfall began to be heard.