This is the second new arena being introduced in Lich King expansion. This arena is a rather small one, and mounting is not allowed.
In this arena, you have to learn to make the environment your friend, else it will be your enemy!
At the start of the fight, each team spawns in a sewer pipe.
Once the match begins, water (You hope, it's a sewer pipe) comes through the pipe and 'shoots' the players into the arena, this is done to prevent camping inside the starting zones. Once inside the arena, water (Again, you hope) levels will randomly rise and fall throughout the arena, meaning you may be swimming for some part of it.
At the roof of the arena is a giant pipe which randomly spurts out more water into the arena, blocking line for some players.