Which park is considered to be the first major water park opened in the united states?

"Wet 'n Wild Orlando"

This water park was founded in 1977 in Orlando, Florida. It was later closed on the 31st of December 2016 and replaced by another called Volcano Bay. George Millay was the creator of it and later received an award from the World Waterpark Association that called him "Father of the Waterpark".