Problem with going late like that is you will miss some of the shows. Not all shows have a night performance. You will still have fun doing things like feeding the dolphins, seals, going on the rides, and watching the walrus and polar bears in Arctic adventure, but they don't always have a sea lion show or dolphin show in the evenings. I think I would check with Sea world to find out showtimes and closing for the day you plan to be there.