I actually emailed Sea World asking about this. Their reply is below:
I am excited to learn that you are planning to visit our Florida Parks and hope you will enjoy all of our wonderful rides, shows and attractions! SeaWorld® and Aquatica™ have clear limitations on what types of food and beverage guests may bring in to the park. Coolers are permitted, but they must be no larger than a soft-sided sixteen (16) quart cooler. The coolers may only contain snacks in individual serving size containers (crackers, chips, fruit snacks, bottled water, etc.) Baby food in plastic containers is also permitted. Sandwiches, pizza, hot dogs, chicken, family size bags of chips, cookies, crackers and soda are not permitted. If you would like to bring a picnic lunch, you must store your cooler in your personal vehicle. Please remember to have your hand stamped at the exit before leaving the park for your re-entry.