Suggestions: How to survive an amusement park in the deed of summer

I have the pleasure of going to an amusement park next week and could really use some suggestions on how not to die of heat exhaustion for two days of pavement walking. Also, any thoughts on going on water slides at the water park. I went to an indoor water park over the weekend and participated. It seemed fine but got some funny looks of a pregnant lady on the water slides. Any input is appreciated!