
Walking into the mouth of Ape Cave feels like stepping onto another planet. Formed about 2,000 years ago, this lava tube is the third longest in North America, and it offers one of the most unique hiking experiences in the Pacific Northwest. It is dark, cool, and surprisingly accessible—if you come prepared. Whether you are looking for an easy family walk underground or a rugged subterranean scramble, this guide covers how to explore Ape Cave safely and comfortably.
Know Before You Go: The Essentials
Ape Cave is not a commercial show cave with colored lights and paved paths; it is a wild lava tube. The environment inside is rough, pitch black, and consistent. A little preparation makes the difference between a cold, short trip and an amazing adventure.
Reservations and Passes
Timed Reservations Required (Seasonal)
From late May through October, you typically must have a timed reservation ticket (purchased via Recreation.gov) to park at Ape Cave. These often sell out on weekends. If you are visiting in the off-season (winter/early spring), no reservation is usually needed, but always check current status before driving up.
Temperature & Gear
The cave stays at a constant 42°F (5°C) year-round. Even if it is 80°F outside, you will be able to see your breath inside. Bring a warm layer (fleece or light puffy jacket) and sturdy, closed-toe shoes. The floor is uneven lava rock, so flip-flops or smooth-soled sneakers can be dangerous.
Light Sources
It is absolute darkness inside. Do not rely on your phone flashlight. The battery will drain quickly in the cold, and the light isn’t strong enough to see the footing clearly. We recommend a headlamp for every person (hands-free is best for balance) plus at least one backup flashlight for the group.
Choosing Your Route: Upper vs. Lower Cave
The main entrance splits into two distinct experiences. You can do one or both depending on your energy levels and group capability.
The Lower Cave (Family Friendly)
Distance: 0.75 miles (out and back)
Difficulty: Easy to Moderate
The Lower Cave is the most popular choice. It is wider, has a flatter floor (though still rocky), and is generally easier to navigate. It takes about an hour to walk down to the “Meatball” (a large block of wedged lava) and back. This is the right choice for families with younger children or anyone who wants the experience without the scrambling.
The Upper Cave (Adventurous)
Distance: 1.5 miles (one way, returns via surface trail)
Difficulty: Strenuous / Scramble
The Upper Cave is a different beast. It requires climbing over large rock piles (breakdown) and scaling an 8-foot lava fall. It is physically demanding and feels much wilder. If you choose this route, you will exit about 1.5 miles uphill and hike back through the forest to the parking lot.
Pair It With: Trail of Two Forests
Just a minute down the road from Ape Cave is the Trail of Two Forests, and it makes for a perfect cool-down or warm-up. It is a short boardwalk loop that winds through a mossy forest filled with “lava casts”—hollow molds left behind where lava hardened around ancient trees.
There is also a “crawl-through” lava cast that kids absolutely love. It is a quick, easy, and fascinating stop that explains the geology you just walked through inside the cave.
For current conditions and access details, check the official page before you go:
Gifford Pinchot National Forest: Ape Cave
Wildlife and Forest Ecology
While the cave itself has very little life (aside from occasional bats or salamanders), the forest surrounding the entrance is lush and active. The transition from the sterile, dark underground to the vibrant green forest is striking.
Please note that white-nose syndrome is a concern for bats in the region. If you have visited other caves recently, ensure your gear has been cleaned according to Forest Service guidelines to protect the local bat population.
Build a Simple Ape Cave Day Plan
- The Classic: Lower Cave walk (1 hour) + Trail of Two Forests (30 mins) + Picnic at the trailhead
- The Workout: Upper Cave scramble (2.5 hours) + Cool down walk at June Lake
- The Full Day: Ape Cave in the morning + Lava Canyon suspension bridge in the afternoon
If you want to keep planning, our main hub page is here: Things to Do Near Mt. St. Helens.