Those things which you can get to from pipes. Waste and water is moved through them. Pretty dang nasty if you ask me. So I have no idea whatsoever why this guy Murlough wants to live down there. Anywho, when Murlough is terrorizing Mr. Crepsley's hometown, Murlough traps Evra down in the sewers. Poor Evra wasn't only kidnapped by this sick Vampaneze, but had to live down in this enviroment. He stayed there until Darren came up with a plan to "sacrifice" Debbie, his girlfriend. Way to make a deal with a guy who wants to kill everybody Darren. You're very lucky it worked and everybody lived.