40 Horse Cave is a fun, family-friendly cave tucked into the rocky walls of Wolverine Canyon, on public BLM land about 15 miles from Firth, Idaho. It's reached by a scenic drive up well-maintained Wolverine Road, with a parking area a couple of miles into the canyon, and there are no fees. The cave gets its colorful name from a pair of local legends — one tells of two men caught in a storm who ducked inside, one remarking that “this cave could hold about 40 horses”; another claims a thief once stashed 40 stolen horses here to avoid capture. Either way, the roomy opening makes the tall tale easy to believe.

The hike up to the cave is short but steep — only about 500 feet long with roughly 100 feet of climbing, yet it earns every step. There are two ways up: the shorter, more direct route is a loose shale scramble that's genuinely slippery (hikers and kids alike tend to slide around, even in good boots), while the slightly longer trail is still steep but holds much less shale and makes for a far easier descent. A common strategy is to grind up the short shale route and come down the gentler one.

Inside, the cave runs only about 25 to 50 feet deep, so a flashlight isn't strictly required — but a few nooks and back corners are more fun to poke around with a light, and kids can easily spend half an hour or more exploring. Keep an eye out for the rock chucks (yellow-bellied marmots) that sun themselves on the boulders around the canyon.

There's more to discover nearby. At the bottom of the trail, a culvert near the road becomes a fun place to splash around when the creek is running high. And if you follow the faint trail in the willows on the southeast side of the road for about 100 feet of easy walking, you'll find a smaller second cave worth a look.

Wolverine Canyon itself is worth the trip. Its rugged rock walls draw rock climbers, the creek and cottonwoods make for pleasant camping and picnicking, and the quiet canyon is good for wildlife watching — deer, raptors, and those ever-present marmots. Many families make a half-day of it, combining the cave with a creekside lunch and a wander among the canyon's formations.

A few practical notes: Wolverine Road is usually in good shape, but it can occasionally be closed to vehicle traffic, so it's worth checking conditions before a long drive. The canyon is a shared landscape of public land and working ranches, so respect any private property and livestock you encounter, leave gates as you find them, and pack out your trash. Bring water, sturdy shoes with good grip for the shale, and sun protection, and enjoy one of eastern Idaho's most enjoyable little cave adventures.