The Hogwarts Swamp is Preserved

PAGES: 848-849

Ginny Weasley tells Hermione that Filius Flitwick has removed most of Fred and George Weasley's swamp, but left a small patch roped off as a monument to their magical skills. Ron mentions that the twins sent him a large stash of Chocolate Frogs, implying that their joke shop business is thriving.