Don Marson, Crystal City Underground tour guide, pours sand into a guest’s hand as he explains the history of the abandoned, submerged sandstone mine, Oct. 21, 2017, at Crystal City Underground in Crystal City, Mo. Marson hosts underground kayaking trips from Scott Air Force Base Outdoor Recreation each month. ( Air Force photo by Airman 1st Class Tara Stetler)

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Size: 4431px × 3165px
Photo credit: © AB Forces News Collection / Alamy / Afripics
License: Licensed
Model Released: No

Keywords: odr