Currently, the sewers of the Magi Castle is being described by 3, if not more players all at once. To prevent things from getting out of hand with it, i will do my part as GM and explain exactly how the sewers work and what is in them. I'll try and make what has already been described by all players work together in a way that doesn't contradict eachother.
The sewers run almost like a maze. There are tunnels upon tunnels, and there are no lights anywhere inside. The only light is from a series of sewer grates that lead up to various parts of the castle. These grates are usually spaces about 20 meters from one another, so finding 2 within close proximity to eachother never happens. If you were to travel far enough through the tunnels, you would get to a point where the grates instead lead up to various parts of Nexus (the capital city of Qortic and the location of the castle) and if you traveled farther still, you would eventually reach the end of the tunnels which empties out into the ocean. Getting to the end from the castle would take a considerable amount of time on foot.
The light from the grates is enough to illuminate the slime on the walls, but only within the immediate area of the grates, and the polluted water in the sewers, which is up to 3 feet deep at some points, but never any shallower than 1 foot deep. It was mentioned that there are uneven stones which rats were seen using to travel through the tunnels. These stones are rather small, and they line the sides of the sewer tunnels. Walking along them would be possible, but you wouldn't be able to move freely on them as you would have to be very careful with your footing or you would fall into the water.
The tunnels are a great amplifier of sound, and can carry noise much farther through the tunnels than what would normally be possible. They don't make noise louder really, they only make it possible to hear the noise from a greater distance.
To sum it up, the tunnels are extremely dark except for where a sewer grate/hatch is found overhead, noise carries much farther, the water is nasty as hell and smells even worse than it looks, making it difficult, if not impossible to smell anything but that, and walking along the stones at the sides of the tunnels is possible, but not practical if you want to move quickly.
I hope this helps all of you out. Just didn't want it getting to confusing for everyone.