SeaWorld Cleveland, originally referred to as Sea World of Ohio, opened to the public on May 29, 1970, after nearly two years of planning and construction. Located approximately 20 miles southeast of Cleveland, in the Western Reserve city of Aurora, Ohio, the 25-acre marine park welcomed over 5,500 guests on its opening day. The oceanarium cost $5.5 million to build, but greatly exceeded the expectations of Millay and his team. In its first 100-day season, SeaWorld Cleveland doubled attendance predictions as more than 1.1 million people visited the park in 1970.