Panel 1: Now that swim time is over, a lady counselor I'll call Lynda tells her very reluctant charges to get out of the water because it's time to get changed for the trip back to town. Since kids are kids, we get the "Awwwww...do we hafta?" thing that is mandatory.
Panel 2: Since she has to explain the obvious to the audience Lynn sees as being morons who need spoon-feeding, she tells them that the yellow buses will be taking them back to the Community Centre in half an hour as they head to the change rooms.
Panel 3: As the kids board the buses, the man with the whistle (who looks a whole lot like a "Bob" so is called "Bob") says that they sure look different from the kids they were when they arrived. Lynda agrees.
Panel 4: This is so she can make a mildly nasty joke about their being clean now.
Summary: What Bob and Lynda don't realize is that one of their kids is really going to look different. This is because she didn't look as if she was going to get flayed alive when she got home by her insane monster of a mother when she headed to the beach.