This thread has been inactive for some time but I just stumbled upon it. I have been going to Myrtle Beach frequently for over half a century. I remember the golden era of small waterparks with a few slides (replaced nowadays by the 3 big parks). On one of my trips with a friend I made it a point to count the waterparks on the entire 60-mile Grand Strand. There were over 20 (it seems like it was 22 or 24). I wish I have recorded more details, like name and location, but unfortunately I just counted.
Bobby G