Yes, you can wear them, but not on the slides. You will have to take them off and hold on to them as you go down the slide.
Crocs work out fairly well in the lazy river and wave pool. As the other poster said, they will make your feet float. When you are walking through the water, it takes a little more effort becuase of the drag that the Crocs cause, so in that sense, water shoes are a little better. But other than that, Crocs are great at the water parks.