5. Splash Lagoon
Location: Erie, PA
This Polynesian-themed ("themed" is a very generous word) indoor water park is the largest in the state of Pennsylvania. In September 2011, they opened a 30,000-square-foot wave pool. They have slides with names like Big Kahuna, Maui Waui, and PJ's Plunge! If that doesn't get you excited, we just don't know what will.