Sewer is found in beginner of challenge mode and in world 3 of story mode in super monkey ball deluxe. The stage is layed out like a fairly easy maze in a halfpipe shape. There are several dead ends and only one passage leads to the goal, meaning that this stage can be tricky at first but once the route is learned, it poses no problem.
If the route is forgotten or unknown, the player can make it up onto the walls by going fast enough, this way the player can see the goal from above. This is the best method of learning the route, atleast on practice mode.