There are a few sites with an umbrella, wooden chairs, and towels available for the day, as well as the cabanas. For any of these they must be reserved and paid in advance, call 407-WDW-PLAY. Some may be available on the day of visit if not rented in advance.
Otherwise, there are a few thousand loungers and lots of umbrellas, but these are on a first-come, first-served, basis.