The Ape Caves are one of the most fascinating places to explore in Washington. You can find these ancient lava tubes in the Gifford Pinchot National Forest, on the south side of Mount St. Helens. At a little over 2 miles long, they’re known as the longest lava tubes in the lower 48 states. The caves feature an upper and a lower level, both of which offer an invigorating hike through the underground.
The caves were formed over 2,000 years ago, when Mount St. Helens erupted and lava poured down the southern flank of the volcano. The lava tubes remain open to visit all year, and can be accessed through Woodland by way of Highway 503. (Read more directions
After descending the steps into the cave, you'll be able to either hike in the upper section (a more challenging route), or in the lower cave, which only goes on for about .8 miles.
The lower section is relatively flat, spacious, and easy for just about anyone to hike. Eventually, it leads to a dead end, where you can just turn around and head back.
On the other hand, the upper cave is a more rugged mile-and-a-half hike. But it is a much more adventurous route, with the lava tube shapes changing more often as you walk through.
The lower cave is most famous for having an unusual feature, known as "Meatball." This block of cooled lava fell from the ceiling when lava flowed through the cave thousands of years ago. It floated downstream with the lava, until it became wedged in the spot we now see it in today.
The upper cave takes a few hours to fully explore. It does require climbing an 8-foot wall, as well as stepping over piles of sharp boulder rocks. Of course, if you aren't comfortable with any part of the trek, you can always turn around and go back.
After about a mile and a half, the upper cave eventually leads to an exit. There is a skylight hole near the end, but if you keep going down you'll find the designated place to leave a little further with a permanently-attached ladder to climb out.
You'll want to be equipped with sturdy shoes, an extra jacket, gloves, and
light sources. You definitely wouldn't want to get stuck in a cold, dark cave with just one broken flashlight.
Nearby, check out the terrifying
Lava Canyon Swinging Bridge