Complex sentence: CIUSA sponsors the famous "Sideshow by the Seashore" which is the last true "Ten in One" performance in the world in addition to the Coney Island Museum, Sideshow School and the annual Coney Island Mermaid Parade, the largest arts parade in America.
Split into simpler sentences: CIUSA sponsors the famous "Sideshow by the Seashore" which is the last true "Ten in One" performance in the world. It alos supports the Coney Island Museum, the Sideshow School, and the annual Coney Island Mermaid Parade, which is the largest arts parade in America.