The School Carnival from the Black Lagoon (Black Lagoon Adventures, No. 7)

Every class has to come up with an idea for a booth at the school carnival. Too bad your class has chosen your idea -- a dunking booth. And they want you to be the one who gets dunked! Boy are you sunk -- because you can't even swim! And to top it all off, you heard there might be sharks in the dunking tank! Yikes!