Eldorado Springs is a census-designated place (CDP) in Boulder County, Colorado, United States. The population was 585 at the 2010 census. The Eldorado Springs Post Office has the ZIP Code 80025.In 1910, Eldorado Springs was a resort community, known for its Big Radium Pool, then the largest swimming pool in the United States. The pool, along with several other smaller ones, was known as "Coney Island of the West."The nearby Eldorado Canyon State Park is famous for its classic North-American climbing routes.