Crystal City underground is a former sand mine, located in Crystal City, Missouri and fronts Plattin Creek, within a mile of it’s intersection with the Mississippi River. It is 6,000,000 million square feet of enclosed underground, which is approximately 200-250 acres. It has 30-40 ft. ceilings. The facility was originally created as a by-product of a sand mining operation. Consequently, thick pillars were systematically cut out of the rock, forming a asymmetrical grid.
The water is crystal clear, and in some areas, it is up to 40 feet deep! The air temperature is in the 50’s (F) and the water temperature is in the 40’s (F).