Ape Cave Interpretive Site

Area Status: Temporarily Closed
This area is Closed

Ape Cave interior with lantern

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. In summer, Ape Headquarters, a small visitor center, offers lantern rentals, information and sales items.

Ape Cave Information

  • It's the third longest lava tube (2.5 miles long) in North America.
  • Cave temperature is 42 degrees F/5.6 degrees C year-round.
  • Be sure to bring: two sources of light per person (cell phone light not bright enough), sturdy shoes, warm clothing, even in summer.
  • No pets, food or drink, except water.
  • Help protect our bats and caves from White Nose Syndrome.
  • Please do not touch cave walls or ceiling. Touching kills cave slime, a basis for the food chain of tiny creatures that live there.
  • Please practice “Leave No Trace” ethics.
  • Ape Headquarters Center, open in summer, provides lantern rentals, information, sales items and White Nose Bat Syndrome information.


Accessible Adventures Video

At a Glance

Current Conditions:

09/17/2020: Ape Cave remains temporarily CLOSED to align with the Washington State "Stay Home-Stay Healthy" Executive Order to prevent the spread of COVID-19. View updates on the closure: www.fs.usda.gov/giffordpinchot/  Forest Road 8303 is gated just past Trail of Two Forests Interpretive Site. Pedestrian and vehicle traffic prohibited beyond the gate.



Permit Info: Dec. l to March 30:  Washington State Sno-Park Permit required at Trail of Two Forests Sno-Park, the winter parking for Ape Cave, and not available on-site. Purchase online or find a nearby vendor. Oregon Snow Park Permits are not accepted.
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)
Passes: April 1 through November 30: America the Beautiful or Northwest Forest Passes accepted.
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.

General Notes:

About Ape Cave

What's in a Name?

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.


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.

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Map showing recreational areas. Map Information



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