The Popo Agie (locally pronounced puh-PO-zhuh) flows down from the Wind River Range, through Lander, Wyoming and on to the Big Horn, Yellowstone, Missouri and Mississippi Rivers. In Sinks Canyon State Park outside Lander, the river abruptly disappears into a limestone cavern from which it emerges a quarter mile downstream before cascading across boulders and into Lander's city park.
The cliffs of Sinks Canyon offer world class rock climbing and the nearby Wind River Range is a haven for hikers, hunter, horsepackers and fishermen. I learned to fly fish on the banks of the Popo Agie from a former NOLS instructor.
Other images from my westward odyssey appear elsewhere on this AFAR collaborative.