Sinks Canyon State Park sits at the base of the southern Wind River Mountains, just a short drive from Lander, Wyo.

In summer, its scenery and sheer rock faces attract mountain climbers, hikers, campers and wildlife watchers. In winter come the skiiers, snow-shoers and snowmobilers.

“It’s a glacial carved canyon. It’s been a corridor for ancient peoples, wildlife, wind, water and ice for thousands of years,” says Darrel Trembly, park superintendent since 1991.

“Every season has its own beauty.”

Its big draw is The Sinks, the place where the Middle Fork of the Popo Agie River disappears into an impressive cavern at the foot of the mountain. Geologists believe the river winds its way through narrow passages and small cracks in the Madison Limestone before re-emerging at The Rise a half-mile away. In dye tests, it takes two hours for water to make the short journey.

(Unless you want to sound like an out-of-stater, Popo Agie is pronounced puh-PO-shuh. It’s a Crow Indian word meaning “gurgling water.”)

The park recently lost its most revered resident, an acclimated Big Horn sheep with a penchant for head-butting parked cars. Read his obituary here.

Last summer, I took 10-year-old Sammy on a mother-son camping trip there. Sarah Trembly, temporary park employee and daughter to the superintendent, led us on a guided tour of Boulder Choke, a cave left the way nature built it. There are no walkways and no lights. The entrance is a pile of boulders barely wide enough for an adult to squeeze through.

The cave extends 1,400 to 1,500 feet – at least that’s the amount that has been mapped and explored. How far you can go depends on how far the water has receded.

Sammy asked Sarah if they’ve ever found anything cool in there — you know, like bones or evidence of a crime scene.

No, Sarah said. Overflow from the Middle Popo Agie wipes the cave clean every year.

It does, though, deposit trout that never find their way out again. Their offspring have adapted to the dark and are now colorless, though they still react to lights directed in the water. Sarah has seen the flashes of white swim away from her beams, though Sammy and I didn’t catch sight of one.

As we walked, crawled or shimmied through the passage, we heard water flowing in rooms either in front, beside or under us. 

Sammy has been to bigger caves in South Dakota. Jewel Cave, for example, impresses with its grated walkways and handrails, its electric lights, its stalagmites and stalactites rising and dropping from ceiling to floor.

But, for Sammy, it doesn’t hold a candle – or a headlamp — to Boulder Choke. There is something to be said about a 10-year-old crawling under low limestone ceilings, knees caked with cold mud. There is adventure in finding your own way around a quiet puddle by a narrow beam of light.

Tours of Boulder Choke must be arranged in advance at the Sinks Canyon Visitor’s Center, and are only available in summer after the water has washed through.

In the meantime, winter still envelopes the canyon. Nearly a foot of snow fell March 22-23, calling to the skiers, snowmobilers and picture-takers. Sinks Canyon’s views are worth a stop, whatever your season.

To read more about the park, go to 

— Kristy Gray

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The features staff of the Casper Star-Tribune — editor Kristy Gray, outdoors reporter Christine Peterson and reporter Benjamin Storrow — are State Guides to Wyoming. The Star-Tribune is Wyoming’s only statewide newspaper and you can follow the adventures of the features folks at and find the Star-Tribune at