Most of the users are under 4 or 5 years old. This therefore comes as a satisfying break from the animal viewing. Suprisingly, this feature is really popular, with parents bringing swimsuits and even wetsuits along. Many parents who don't bring swimwear along tend to leave their kids to run around in their underwear or even naked, but this isn't appropriate in a zoo, and brings up the issue of security above anything else.
I'd have preferred swimming inside the Lubetkin penguin pool...
Kids under 5 in underware, okay, i accept it when they have this, but naked, that is unacceptable (was there any naked people there when you were there?)
I just think its inappropriate behaviour, I've seen it briefly a couple of times (granted, only when it was really crowded and the children might well have been running away whilst their parents were getting them changed) but its ultimately the parents' responsibility to protect their children from any possible harm when in such a public area.