The Bug City and Waterworld area is an extra charge, and consists a a dozen or so invertebrate tanks, half-a-dozen reptile displays and five fish tanks.
If it was part of the main park it would be quite a nice addition, but it's not really worth paying extra for, in truth.
The Waterworld part of this area consists of these four open-topped displays and a tank for Peter's Elephant-nosed trunkfish. The fish here include a Red-tail Cat that looks like it may be a rescue animal - it'll need rescuing from here before too long as it's on the point of outgrowing the tank.