My number one tip for visiting the Dolphin Discovery Centre down in Bunbury is to go early. The dolphins usually visit between 8 and 10 am. They’re wild, so there’s no guarantee that they’ll come even then, but you’ll be giving yourself the best chance of seeing them and avoiding the bother of waiting all afternoon for an appearance because you slept in and got there after they had come and gone, driving back to Perth with a grumpy family then driving back to Bunbury at the crack of dawn two days later to redeem yourself. Probably best to avoid that.
And if they do come, you’ll be waist deep in water, so dress appropriately. Speaking from experience I can say that a pair of chinos are not entirely the best choice.