They do, but because many of their things are shows, people have generally not posted a lot about needing a GAC (Guest Assistance Card, for people reading this who are not familiar with the letters). This past thread has information about Sea World. One of the posts on page 2 talks about GACs. In page 2 of that thread there is a link to the Sea World accessibility Guidebook (don't feel bad about not finding it on their website, it's not very easy to find). This is a direct link to that Guidebook. It will load as a pdf file. The page it loads to is apparently a blank part of the cover; just scroll down a bit and the text will show.
If you lose these links, go to the disABILITIES FAQs thread and you will find the links in post #10 of that thread.