Ape Cave Interpretive Site

Area Status: Open
This area is Open

Ape Cave Entrance

Ape Cave sits among a mixed-species forest stand. A short, paved trail leads from the newly remodeled and accessible parking lot with visitor center and facilities to the caves lower entrance and interpretive area. The trail continues on to the upper entrance, though it becomes more steep and rough.

Accessible Adventures Video


Ape Cave Information

  • The Third Longest lava tube (13,042’ long) in North America
  • Be sure to practice “Leave No Trace” ethics
  • Cave temperature is 42°F/5.6°C year-round
  • Ape Headquarters Center provides:
  • Be sure to bring:
    • Two sources of light per person
    • sturdy shoes
    • warm clothing

At a Glance

Current Conditions: 11/24/2015: Cave open daily. Ape Headquarters Center closed for season. Bring your own light sources.
Operational Hours:
  • Ape Cave is open year round. In winter, park at Trail of Two Forests and walk about a mile to the cave. A Washington State Sno-Park Permit is required to park starting December 1. Winter visitors need to bring a recommended 2-3 light sources to explore the cave.
  • Ape Headquarters Center should reopen Memorial Day Weekend, 2016. Open weekends 10 am to 5 pm until the end of June when it will be open 7 days a week. After Labor Day, open weekends through September.
Rentals & Guides:

Lantern Rental: $5 at Ape Headquarters Center. Center is closed for the winter. Bring your own light sources.

Fees Recreation Pass Required
Permit Info: A  Washington State Sno-Park Permit is required during the winter season, December 1 through March 31, to park at the Trail of Two Forests Sno-Park. Sno-Park Permits are NOT available at the site. Oregon Snow Park Permits are no longer accepted.
Restrictions: To protect the cave enviroment please, NO Dogs, Pets, Food, Alcohol, Fireworks, Fires, Camping or Smoking are allowed in Ape Cave. Please be advised the inside of cars can get very hot during the summer months and is not a safe place for your pets.  Please leave your pets safe at home.
Closest Towns:

Cougar, WA

Water: No
Restroom: Vault Toilet (2)
Passes: Recreation Passes may be used as a form of fee payment, except during December 1 to March 31 when a Washington State Sno-Park Permit is required to park at Trail of Two Forests Sno Park. Sno-Park permits are NOT available at the site.
Operated By: Forest Service
Information Center: Mount St Helens National Volcanic Monument Headquarters and Visitor Centers   See also:  South Side - SR 503, Forest Roads 83 & 90

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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