As spring gives way to summer, families start thinking of staying cool in the heat. The obvious places to go are the beach and the pool, but when those start to bore the kids, plan a trip to the water park. Many modern water amusement parks combine the best elements of theme parks and a day at the beach. Water slides are no longer the 15 second, stick-and-go ride with a piece of Styrofoam from yesteryear. These new parks continuously find new and innovative designs to draw visitors. The largest single-person drop slide, for example, plunges 120 feet. Schlitterbahn Waterpark in Texas has perfected the uphill ride, and Six Flags White Water in Atlanta is famous for its thrilling "Tornado". As visitors expect more, the parks deliver. Many of them encompass 20 acres or more, with the largest in the United States spanning 70 acres. Besides coasters and slides, they now include kiddie pools and playgrounds, lazy rivers to float down, surf machines and wave pools. And water-themed ...