I hinted pretty strongly in Wednesday's headline for the Mystery Photo, for tigers have stripes as dark as those in the photo. But most national park travelers won't spot this sight, for it takes a river trip to reach it. But for those who paddle the Yampa River through Dinosaur National Monument, the Tiger Wall is well-known.

Throughout the canyons that the Yampa flows are countless examples of "desert varnish," those black streaks of manganese and iron oxide deposits formed by runoff coursing down the white sandstone cliffs. But the Tiger Wall stands out, no doubt in large part due to its location right on the river. It's said that a safe river trip can be guaranteed if those paddling by kiss the wall, which is right around river mile 9, before heading on downstream.

The Yampa River flows along the very northern edge of the Colorado Plateau. Enter this landscape and it can surprise you, as it's located in northeastern Utah and northwestern Colorado and yet boasts a towering, and colorful, landscape more commonly found farther south in Arches, Canyonlands and Grand Canyon national parks.

Since there are no dams on the Yampa, its flow is entirely runoff dependent. For rafters that means trips starting as early as April when there's still snow in the high country -- and sometimes even falling on the river. By early July the water levels generally are too low for rafts, but deep enough for canoes and kayaks. Although, I've heard the bugs can be pretty atrocious in summer.