Lost Island Waterpark is a tropical oasis in a sea of corn fields, and for 15 years, one of Iowa’s best-kept secrets. Located in Waterloo, Iowa, not too far from Des Moines and Cedar Rapids, Iowa, the water park is open seasonally for summer fun, with water slides, lazy river, splash zones, a wave pool and water coasters. The park also offers mini-golf, go-karts, zip lining and arcade games. The water park is located near Waterloo KOA Kampground for accommodations.