Ape Caves & Trail of Two Forests

A relatively short drive from Portland up highway 503 past Cougar, lies a series of lava tubes on the south side of Mt.Saint Helens. Ape Cave Lava Tube is a popular attraction in the Mount St. Helens National Monument and the longest lava tube in the continental United States at over two miles in length.


The Hike: The Ape cave is divided into two sections Lower (easy) and Upper Cave (Hard). The lower Ape Cave is approximately .75 miles long and can be hiked down and back in an hour.  It is most famous for Meatball – a block of cooled lava which fell from the lava tube ceiling while lava was still flowing through the cave.   Floating on the surface of the lava flow it was carried downstream until it became wedged in a narrow spot above the present cave floor.

Another feature is the Railroad tracks – a shoulder or levee that formed along the side of the lava flow. As the fluid lava drained out of the tube, the levee remained.  Lava stalactites and stalagmites and flow marks can be seen on the walls and floor of the cave.   Lava stalactites, conical or cylindrical deposits of lava that hang from the ceiling of a tube, are formed by dripping; stalagmites are similar in shape and are formed on the floor of the tube by the accumulation of drips from the ceiling.

The upper Ape Cave is 1½-mile long and takes about 2½ hours to complete,
returning on a surface trail. We didn’t get to this section this time as we arrived pretty late in the day. This section is more adventurous as cavers must climb
over approximately 27 boulder piles and scale an 8-foot high lava fall.

The boulder piles formed after the eruption subsided and the fluid lava drained from
the tube. As the lava tube cooled, it began to shrink and crack. These cracks
weakened the ceiling and walls causing parts of them to collapse – forming
entrances to Ape Cave. *Note there is a skylight hole in the tube near the upper
exit however the trail continues on through the tube to a permanently attached
metal ladder.  Exiting the cave through the skylight is off limits.

Upper Cave Map

Before we head over to the next hike a few things to keep in mind when visiting Ape Caves:

  • No food, beverages, alcohol or
  • No smokingNo flares, fireworks,
    firearms or any kind of open flame
  • No rock collecting or damaging cave
    features ($200 fine).
  • No pets !
  • Do not touch the walls – Cave “slime”
    lives on the cave walls and is an
    important food source for cave life.



Area Vicinity Map

Next we headed over to Trail of Two Forests, Which is a very short I wouldn’t even call it a hike it’s about a half mile lollipop loop on a boardwalk to preserve the fragile mosses and surrounding features of the forest. This trail loops through two forests that stand side by side, but are separated in age by 2000 years. One forest is old-growth Douglas-fir and western red-cedar and the other is a young forest that was originally engulfed by lava flows from an eruption of Mount St. Helens over two millennia ago.

The other forest, known formerly as the Lava Cast Forest, encompasses three-dimensional imprints of trees in the old lava beds called lava casts. The boardwalk trail loops through the two forests. During eruptive activity some 1900 years ago, fluid lava flowed through a stand of trees, burning them but leaving impressions where they stood or lay. This lava was quite different from the sticky type of lava that forms the dome in the crater of St. Helens today.

Regardless of the difficulty level this place is magical and fun to explore. One attraction along the boardwalk is a ladder descending eight feet into a lava-cast tree mold. Hikers can crawl through the tree mold. Would suggest a head lamp and old, warm clothes as good preparation for the fun. Although very short if claustrophobia plagues you I probably would just admire the impressions from above, the caves are quite the tight fit and although short still very dark.

This trip was a fun fall day and to top it off it was a fee free day since it was national Public lands day. However, If your not so lucky its only a $5 parking fee to visit for the day with only a mile separating each other they are the perfect pairing for a trip to Mt. Saint Helens.


  1. BRE this is Joey Garcia , your moms cousin , I love reading your blog. I went to yosemite last year with my girlfriend she loved it, and I may travel up the coast to visit good friends in Portland! I’ll let you know when I go” 🗽


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