Ape Cave Interpretive Site

Area Status: Open
Visitors ascending the stairs leading out of the cave

Explore a chilly, pitch-black lava tube over two miles long. A short, paved, accessible trail beneath towering trees leads to a stairwell into the cave. The ¾ mile, one-way lower cave route is relatively easy and family friendly. For the more adventurous, the 1.5 mile upper cave route leads to a climb up an eight foot rock wall and scramble over rock piles, then an exit and a 1.5 mile above ground hike back to the parking lot. 

Ape Cave is the third longest lava tube (2.5 miles long) in North America and cave temperature is 42 degrees F/5.6 degrees C year-round. Make sure to bring two sources of light per person (a cell phone light is not bright enough), sturdy shoes, warm clothing, even in warm weather. In summer, Ape Headquarters, a small information station, offers lantern rentals, information and sales items to ticket holders.

Help protect Ape Cave. Please do not touch cave walls or ceiling. Touching kills cave slime, a basis for the food chain of tiny creatures that live there. Help protect our bats and caves from White Nose Syndrome. Practice Leave No Trace principles by packing out all that you bring with you.

Reservation System: Timed reservations are required to visit Ape Cave during the open season: May 18 Cave through October 31. Choose a two-hour time slot for your desired day on recreation.gov ($2 admin fee). 

Reservation System, Frequently Asked Questions: English, Spanish, Russian.

Accessible Adventures Video (Ape Cave description at 1:58)

Inside the lava tube that is Ape Cave Rustic forest interpretive building. Interior of the large cavernous Ape Cave Boulders along the bottom of Ape Cave

At a Glance

Current Conditions: 05/24/2024: Ape Cave is open for the season and timed reservations are required during the summer season, and must displayed on your vehicle dash. Timed Reservation tickets are available at recreation.gov. During the winter, it is illegal to enter Ape Cave without authorization, 36 CFR 261.53 (b). 
Reservations:   Timed reservations are required to visit Ape Cave during the open season from May 18th to October 31.
Fees: $5/vehicle/day or valid Recreation Pass. Fee tube available for payment on-site. See Mount St. Helens Map for fee and payment sites. A timed reservation is also necessary and may be booked through recreation.gov starting April 15. 
Usage: Heavy
Restrictions: In order to protect the fragile cave environment, the following are prohibited inside Ape Cave:
  • Pets
  • Food or Drinks (except water)
  • Alcohol
  • Fireworks
  • Fires
  • Camping
  • Smoking
Please be advised the inside of cars get very hot during summer months. Please leave your pets safely at home.
Closest Towns:

Cougar, WA

Water: No
Restroom: Vault Toilets (2)
Operated By: Forest Service
Information Center:

General Information


From Woodland, WA take State Route 503 to Cougar WA then take Lewis River Road east for 2.8 miles. The road then changes to Forest Road 90. Continue on Forest Road 90 to Forest Road 83, approximately 4 miles and turn left. Drive Forest Road 83 for 3 miles then turn left onto Forest Road 8303. Drive approximately 1.5 miles, past Trail of Two Forest, Apes' Headquarters is located at Ape Cave on Forest Road 8303 on the left.


The parking lot and visitor area facilities are flat and paved. A paved trail leads to the lower cave entrance, but gets rougher to reach the upper entrance.

Recreation Map

Map showing recreational areas. Map Information


Day Hiking

Recreation areas with activity Day Hiking:


Recreation areas with activity Caving:

The lower cave is the more popular route with its fairly level, mudflow-covered floor. Highlights include “railroad tracks” and the "meatball." Allow at least an hour to complete the 1.6-mile round trip. The upper cave travels over large rock piles and requires scaling of an 8-foot lava fall.

Two-thirds of the way up you will pass beneath The Skylight, an opening to the surface. Do not try to climb out; this is NOT an exit. The upper entrance is only 0.25 mile ahead.

Allow 2.5 hours for travel through the upper cave to Ape Cave Trail #239. 

To help stop the Spread of White Nose Syndrome and to Help Keep Our Caves Open please decontaminate your clothing and equipment before visiting from another cave. Please see Keep our Caves Open for more information on WNS.

General Info:

General Notes

About Ape Cave

Ape Cave was discovered in 1947 by a logger named Lawrence Johnson. However, the cave was not explored until the early 1950's when a scout troop, led by Harry Reese, lowered a team of scouts down a 17-foot overhang to the cave floor. Leaving footprints where no one ever had, these explorers were able to travel through a pristine lava tube full of fragile formations. Ape Cave was named by the Scout Troop in honor of their sponsor, the St. Helens Apes. This local group was made up primarily of foresters. The sponsor’s name, St. Helens Apes, may have come from an old term used for foresters in the area, "brush apes," or from the legend of Bigfoot.

An Uncommon Eruption:

The formation of Ape Cave marks an unusual period in Mount St. Helens' eruptive history in that it is the only known basaltic eruption of the volcano. Eruptions of fluid basaltic lava, much like those in Hawaii, are rare occurrences in the Cascade Mountain Range. The Cascades usually erupt lava of a thicker consistency. When this type of magma is coupled with suspended gases, explosive eruptions tend to occur. The eruption of Mount St. Helens on May 18, 1980, exemplifies this tendency.

About 2,000 years ago, fluid basaltic lava poured down the southern flank of the volcano. As the lava flowed, chunks of the lava’s surface cooled, crashed and fused together creating a hardened crust. In turn, the crust insulated the molten lava beneath, allowing it to remain fluid and travel down to the Lewis River Valley. The hot flowing lava began melting into the pre-existing rock and soil. This thermal erosion deepened and widened the channel of the flow. The level of lava in the tube rose and fell as the eruption surged and slowed, contributing to the unique contours of the walls. During this eruptive period, hot fluid lava pulsed through the tube for months, possibly up to a year, until the eruption subsided. As a result of this rare eruption, a spectacular 13,042 foot (3976m) long lava tube, the third longest in North America, was created.

Visitors exploring the dark interior of the lava tube with flashlights

Interpretive Areas

Recreation areas with activity Interpretive Areas:

Formed 1,900 years ago and first explored in the early 1950s by a local scout troop, the cave was initially the longest known lava tube in the continental United States.

Apes' Headquarters, a Forest Service building near the cave entrance, provides lantern rentals during the summer.

Related Information

Recreation Areas

Recreation Activities


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