The legendary portable swamp created by Fred and George Weasley was once large enough to consume the entire fifth-floor corridor. Needless to say, this greatly irritated the notorious Dolores Umbridge when there were no instructions on how to remove it and the then teachers didn't seem to mind that it was there. Today a small section of the swamp remains, roped off in tribute of the redheaded twins' historic act of protest.

When you are getting close to this reserved section of the corridor, you will know without question. The remaining swamp still smells like an authentic swamp, look like an authentic swamp, bubbles like an authentic swamp, and will indeed suck you in if you cross over the rope and step in it. Avoid the Weasley swamp with care is the best advice you should heed while on the fifth floor, especially if you're running late to class. While it must have been an impressive and humorous sight back in the mid-90's, just praise Merlin that you don't have to make your way across today.