My DD (3) has been there a few times, and always wears a life vest in the pool. I got it at Target - not very expensive but it fastens around her chest and then between her legs and she did great, even going down the slide. It also is sufficient that if she jumps in from the side it keeps her upright like she is treading water, even in rough waters around fountains and bigger kids playing. I pack it in the suitcase with her clothes stuffed inside so it really doesn't take much room. We were never asked to not use it, but it is not like the blow up arm things - not sure about those, if there are any rules.