Pets allowed
Not Allowed
Elevation Gain
200.00 ft (60.96 m)
Trail type
2.00 mi (3.22 km)
Please respect the outdoors by practicing Leave No Trace. Learn more about how to apply the principles of Leave No Trace on your next outdoor adventure here.

With a total length of more than 2 miles, Ape Cave is the longest lava tube in the continental United States.  Located on the south side of Mount St. Helens, the site offers routes through both the upper and lower tubes of Ape Cave.  Both tubes remain a constant 42 degrees Fahrenheit throughout the year.

You will find an ample amount of informational and educational signs at the trailhead, at the mouth of the cave, and along the forest trail, all of which directs you to the cave of your choosing and back to your car. The easier of the two choices, the lower tube, is less than a mile long and can be hiked down and back in approximately one hour. The upper Ape Cave is 1 1/2 miles long and will take more than two hours to complete, which includes returning to the parking lot via an above-ground trail. The upper tube is clearly a more adventurous route, as this section of the cave requires scrambles over a number of boulder piles and ducking through some tight passages.

Ape Cave is open year-round, although winter access may require a hike in with snowshoes. No matter what the weather conditions are outside, the caves will always be a damp-and-dark 42 degrees, so be sure to bring warm clothing as well as a headlamp and/or flashlight with backup batteries.

Logistics + Planning

Preferable season(s)




Parking Pass

NW Forest Pass


Longest lava tube in North America. Consistent climate in the caves.


Variable winter access. Visibility and temperature not optimal for all ages.

Trailhead Elevation

2,275.00 ft (693.42 m)


Historically significant
Old-growth forest


Nearby Adventures

Southwest Washington/Mount St. Helens, Washington
Southwest Washington/Mount St. Helens, Washington
Southwest Washington/Mount St. Helens, Washington

Nearby Lodging + Camping

Southwest Washington/Mount St. Helens, Washington
Southwest Washington/Mount St. Helens, Washington
Southwest Washington/Mount St. Helens, Washington


A great family activity on a warm, summer afternoon!
Second time there and it is a blast. It is easier to begin the hike at the main entrance. It might seem like going the other way makes sense, however it is a little harder getting down some the tight or higher sections.

Also please make sure to pack proper lighting for the Upper Passage. Cell phone lights work (poorly), but you have water dropping from the ceiling, cracks your phone can fall through, and plenty of opportunities to drop it and be in the dark hoping someone comes along.
Hiked up to upper entrance and went back through cave to main entrance. Went on a Monday early morning, had the cave more or less to myself. Such a fascinating hike to imagine how it was created!! Wear proper footwear, rarely easy walking through cave, but lots of fun scrambles over rocks!
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