Mammoth Cave

Mammoth Cave is closed to entry every year from October 1 through April 30, when Townsend's big-eared bats hibernate inside, so plan it for summer or early fall. When it is open, it is one of the largest lava tubes in Utah: over 2,200 feet of passage at about 8,050 feet on the Markagunt Plateau, formed by cooling lava and flowing water, some of it only a few thousand years old. From the surface it looks like a big hole in the ground. Below, nothing is developed — no lights, no handrails, no walkway. The Forest Service asks for a good light for every person, and it means it, because the cave goes pitch dark after the first turn. The far exit is a small tube with only enough room to slide through on your belly, so if you are broad-shouldered or claustrophobic, turn around and walk back the way you came.

Highlights

• Over 2,200 feet of passage in one of the largest lava tubes in Utah
• Closed to entry October 1 through April 30 for hibernating Townsend's big-eared bats
• About 8,050 feet elevation on the Markagunt Plateau; some of the lava is only a few thousand years old
• Completely undeveloped — no lights, no stairs, and pitch dark past the first turn
• The exit is a belly-crawl tube; you can always turn around and return the way you came
• Bats use the cave as a nightly summer roost, along with small birds and mammals

Tips

Carry a good light for every person and a spare set of batteries — the Forest Service spells this out for a reason. Water seeps in near the back and glazes the rock, so wear real hiking shoes rather than sneakers. Move quietly, keep your beam off any roosting bats, and leave the rock where you found it. If you are not sure the seasonal closure has lifted, call the Cedar City Ranger District at 435-865-3200 before you make the drive.

When to go

Spring Summer Fall Winter

Entry is prohibited from October 1 through April 30 each year for hibernating bats, which makes summer and early fall the only window. Snow lingers on the access road into spring and the last stretch is dirt, so give it time to dry out. Late June through September is the dependable stretch.

What to bring

• A good light for every person, plus a spare — this is the one rule the Forest Service spells out
• Shoes with real tread; seepage at the back of the cave leaves the rock slippery
• Long sleeves and a warm layer for the moment you drop below ground
• Gloves and clothes you do not mind scuffing on rough basalt

Stay planning

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