suprisingly enough, it's the kind of place you'd walk around a couple of times and get bored of it. the tunnel has a conveyor running so you could just stay on there for a while, they feed the sharks at lunch time, do diving trips "dive or snorkel with the sharks" when people want to pay enough. also seals and a touchpool for the kids.
When you get a big group together they have kids sleep overs where everyone sleeps in the tunnel under all the fish and sharks.
Used to have dolphins but they were released back into the wild, I think one keeps coming back every now and then.
glad you like and if your ever in aus, gimme a call