Lost Island Theme Park is a theme park in Waterloo, Iowa. The 90-acre (36 ha) park includes five themed lands, which feature numerous attractions; including three roller coasters. Lost Island Theme Park is owned by the Bertch family, who operate the Lost Island Waterpark, which is located next to the site of the theme park. Construction on Lost Island Theme Park began in August 2019, it opened on June 18, 2022, and it cost an estimated $100 million.