The Disney park is one of almost 2,000 water parks that have cropped up around the world in the past 30 years. The once-simple backyard pool accessories—remember those light blue, 6-foot-tall (2-meter-tall) slides?—now have hairpin curves, exhilarating loops, and drops that span multiple stories.

The waterslide even plays a starring role in the critically acclaimed summer movie The Way, Way Back, which opens this Friday. In the poignant coming-of-age story, 14-year-old Duncan (Liam James) escapes his complicated family life by working in a highly chlorinated summer water park, where he makes good friends and escapes his troubles by plummeting down slide after slide.

At National Geographic, we enjoy a good waterslide (who doesn't?) but were also wondering just how they work—and how water parks use