I have been twice and did not see many of the cabanas. First trip the park was virtually empty, maybe only a couple hundred people. There was an empty one. Last trip the park probably was not full, but I would guess half or more full, there were no cabanas left that I saw. If you truly want one, I would call ahead and reserve it.
From their site:
Private cabanas are available for rental at an additional fee and are tucked within the lush landscaping overlooking the Dolphin Lagoon. Complete with table and chairs, chaise lounges, and rolled towels, the cabanas provide a special place to relax when not in the water exploring.
For additional information please call 1-877-557-7404
Food was all you could eat.......cafeteria style and they do not check you out or anything.