It is posted that you need swim diapers. (If you're not familiar with them, they are disposables that you can find in the stores right next to the regular diapers.) One of the two times we swam during our last trip the lifeguard said that they needed to have swimsuits OVER the swim diapers. I did not see this anywhere, and he finally let us just put a pair of knit shorts over the swim diaper, but he was not willing to let us in otherwise.

(It was December and he had outgrown his suit from the summer and I didn't buy one just for the winter trip, knowing that he'll need a larger size yet this summer.)