This video shows the Middle Fork of the Popo Agie River as it flows into a limestone cavern and disappears below ground into a network of narrow fissures (the sinks); it re-emerges 1/4 mile downstream in a shallow pool (the rise), then continues northeastwards towards Lander. The sinks, the rise, and 3.5 miles of the valley are contained within Sinks Canyon State Park. (mp4; 0:52 min; 7 mb)