APE CAVES - Mt. St. Helens Lava Tube
MountStHelens.com Information Resource Center
Mount St. 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 Ape Caves are located on the south side of Mount St. Helens and accessed
through Woodland - go up highway 503 past Cougar. Driving time from I-5 and highway 504
where all the Mount St. Helens Visitor Centers are to the Ape Cave is just over an hour. The Ape Caves are open yearround though the parking lot gets snowed in during the winter.
Hiking the Ape Caves: The lower Ape Cave is approximately is .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. 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. During the
summer, a national monument interpretive naturalist leads tours through the lower part of the cave. Recommended
equipment for exploring the Ape Caves is sturdy shoes or boots,
warm clothing, and three sources of light.
13,042 Ft. LONG !
Ape Cave Hiker USFS Regulations:
 No food, beverages, alcohol or littering.
 No smoking, No 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.
How the Ape Caves were formed: About 2,000 years ago lava poured down the southern flank of Mount St. Helens in
streams. As the lava flowed the outer edges of the lava stream cooled forming a hardened crust which insulated
the molten lava beneath. This allowed the lava to remain hot and fluid encased in this “lava tube” and continued flowing
months during the eruption. The end result was the creation of this spectacular 13,042 long lava tube. This formation is
especially unusual at Mount St. Helens as this type of volcano usually erupts lava of a much thicker consistency which
tends to block flow and build up pressure resulting in explosive eruptions like the blast of 1980.
Watch out for the Wild Apes ! Mount St. Helens has long been famous as an area of frequent Bigfoot,
Sasquatch or “Hairy Ape” sightings. Nearby “Ape Canyon” was the sight of the famous reported
skirmish between Miners and a family of Bigfoot back in 1924. The incident has become a legend in
the Northwest – here is the bigfoot story from one of the miners - "I FOUGHT THE APEMEN OF MOUNT
ST. HELENS, WA". However, I wouldn’t worry too much about seeing bigfoot in the Ape Caves –
common lore attributes the name to a scout troop who explored the caves back in the early
50’s. Apparently the troop’s sponsor was the St. Helens Apes – a group of foresters.
Foresters and loggers in those days were sometimes referred to as “Brush Apes”. Perhaps this is the
origin of the name though those that have claimed to have seen bigfoot in the area believe the caves
would have been a perfect habitat for the reclusive creatures.
Ape Headquarters Opened June 9 for the season.
Fee: During the summer, a Northwest Forest Parking Pass
is required - $5/day, $30/season. When snow comes, a sno-park
pass is required and cavers must walk/snowshoe about one mile
from the Trail of Two Forests parking area. Passes can be
purchased at the store in Cougar and also at Johnston Ridge
Observatory. The annual pass also admits one to Johnston Ridge
Observatory.