Balmorhea State Park Pool

The world's largest spring-fed swimming pool, fed by the San Solomon Springs, was built in the 1930's by the Civilian Conservation Corps. 

With strikingly clear water, a depth of up to 25 feet and a temperature of 72-76 degrees, it is ideal for both swimming and scuba diving. A consistent churn of over 22 million gallons of water a day flows through the pool, meaning it needs no chlorination. The popular stop at Balmorhea State Park was part of the New Deal, FDR's Depression-era plan to create jobs. The CCC operated from 1933 to 1942, creating manual labor for unskilled, unemployed men and preserving and developing the country's natural resources.