The Fault Caves are an unusual and adventurous cave system in the foothills above Golden, Colorado, just off U.S. Highway 6 in Clear Creek Canyon. Unlike most caves — which are carved by water, wind, or lava — these formed along a fault line, where movement in the rock cracked open a maze of narrow fissures, tunnels, and chambers through the mountain. The result is a genuinely challenging warren of tight, winding passages that has become a favorite proving ground for Front Range cavers.

From the highway pullout, a short but steep, rocky scramble leads up to the entrance — a well-worn route that involves finding footholds and clambering over boulders, so it's more of a climb than a walk. The cave mouth is easy to spot once you're close: it's ringed with graffiti. Inside, a central main chamber branches into offshoots that connect to nearly everywhere else in the system; some passages you can walk like a narrow hallway, while others must be crawled through carefully and are scarcely wider than your body. A rope hangs in one spot to help climb between levels, and some of the tightest squeezes — including a notorious narrow “V” — will genuinely test larger cavers.

This is not a beginner's cave. The passages are tight, complex, and easy to get disoriented in, so it should be explored only by experienced cavers or in the company of someone who knows the system. Bring at least two light sources per person — a headlamp plus backups — since you'll need both hands free to crawl and climb. Seasoned cavers strongly recommend gloves, long sleeves, and long pants: the dirt holds a lot of broken glass, and the rock is rough. Watch your footing especially on the way out, where you have to haul yourself up and over a large boulder to exit the main chamber — a spot that has turned more than one ankle.

Crucial seasonal closure: the caves lie within Jefferson County's Clear Creek Canyon Park, and the county closes the area above Highway 6 to all public use from February 1 through July 31 each year to protect nesting eagles and other raptors. Plan your visit for August through January, and check the Jefferson County Open Space alerts before heading out, as the closure boundaries can shift with the birds.

The caves are dry and dusty — conditions that have kept stalactites and other formations from developing — and, sadly, they carry a fair amount of graffiti and litter; pack out everything you bring and consider hauling out a little extra. Wear sturdy shoes, dress in layers, tell someone your plans, and for those with the experience and the nerve, the Fault Caves offer one of the most exciting little underground adventures on the Front Range.