[Sioned]

We go to Seaworld quite a bit. We have never had a problem taking unopened water bottles, crackers and sandwiches in a small backpack each. They do search bags at the entrance. I do not know what the official policy is, you should check the website, which also has a schedule of showtimes as getting to see all the shows you want takes a bit of planning. People start lining up for the shows at least 30 minutes early in the summer.
You can also keep a cooler in your car and go out to the parking lot - park by a tree - which will take the same amount of time as lining up in a restaurant. You pay $10 parking - you might as well get your money's worth.