Ape Cave
About
What It Is
Ape Cave is a lava tube located within Mount St. Helens National Volcanic Monument, part of Gifford Pinchot National Forest in Washington State [1]. At 2.5 miles in length, it ranks as the third-longest lava tube in North America [1][2]. The cave maintains a constant temperature of 42 degrees Fahrenheit (5.6 degrees Celsius) year-round and is entirely dark inside [1][2]. It is managed as an interpretive site open to self-guided public exploration during a defined seasonal window [1].
Activities & Experiences
Visitors can explore one of two routes inside the cave [1][2]. The lower cave is a 3/4-mile one-way route that is relatively easy and suitable for families, with most visitors completing it in about an hour [1][2]. The upper cave is a 1.5-mile route that involves scrambling over rock piles, scaling an eight-foot rock wall, and exiting through a small opening at the ground surface, followed by a 1.5-mile above-ground hike back to the parking area; this route typically takes two hours or more [1][2]. A short paved accessible trail leads from the parking area to the cave entrance stairwell [1].
Practical Access
Ape Cave is located on Forest Road 8303, approximately 9 miles east of Cougar, WA [2]. The site is open seasonally from May 18 to October 31, with operating hours of 9 AM to 5 PM [1]. Timed entry tickets are required for each vehicle and must be reserved in advance at recreation.gov; tickets cover a two-hour exploration window [1][2]. A day-use parking fee of $5 per vehicle applies, or visitors may use a Northwest Forest Pass or America the Beautiful Pass [1][2]. A $2 administrative fee applies to each reservation [1]. Ape Headquarters, an on-site information station, is open seven days a week from 9 AM to 5 PM during the open season and offers lantern rentals, snacks, books, and gifts [1][2]. Vault toilet restrooms are available on-site, but running water and drinking water are not [2].
Restrictions
The following are prohibited inside Ape Cave: pets, food or drinks other than water, alcohol, fireworks, fires, camping, and smoking [1]. Visitors must bring two independent light sources per person; cell phone lights are not considered adequate [1][2]. Ticket holders must arrive no earlier than 15 minutes before and no later than 30 minutes after their reserved entry time; late arrivals may be denied entry [2]. Visitors are asked not to touch cave walls or ceilings, as contact damages cave slime that supports the cave ecosystem [1]. Leave No Trace principles apply, and all items brought in must be packed out [1]. The cave is closed to the public from November 1 to May 17, with no access permitted without prior authorization under 36 CFR 261.53(b) [1]. Organized school groups and scout outings must register separately through MSHNVM.org [2].
What Makes It Distinctive
Ape Cave is one of the longest lava tubes in North America, offering a rare opportunity to walk through a geologically significant underground passage formed by volcanic activity associated with Mount St. Helens [1][2]. The dual-route structure allows visitors of different ability levels to engage with the same cave system, from a straightforward family walk to a physically demanding scramble [1][2]. The year-round constant temperature and complete darkness create an environment unlike surface natural attractions, requiring visitors to come equipped and prepared regardless of outside weather conditions [1].
Sources
- Gifford Pinchot National Forest | Ape Cave Interpretive Site | Forest Service
- Ape Cave Interpretive Site Ticket, Gifford Pinchot National Forest - Recreation.gov
- Season: June–September
- Typical duration: 4h
Access & fees
- day-use parking $5/vehicle
- day-use vehicle fee
- no drinking water on-site
- pass alternatives accepted
- reservation admin fee
- timed-entry reservation fee
Things to do
- adventure hiking
- cave exploration
- explore the lower cave
- explore the upper cave
- geology observation
- lava-tube exploration
- lower cave self-guided walk
- nature interpretation
- photography
- spelunking
- underground hiking
- upper cave self-guided exploration
Amenities
- ape headquarters visitor station
- flashlight rentals on-site
- vault toilets available
Best time to visit
- open season only
Features
- constant cave temperature
- paved accessible entrance trail
- third-longest lava tube, north america
Nearby
- cougar, wa
Good to know
- ape cave has seasonal access and timed-entry requirements during the main visitor season
- arrival window enforced
- bring at least two reliable light sources per person, such as a headlamp plus a flashlight. cell-phone lights are not adequate.
- operational hours
- pets prohibited inside cave
- site closed in winter
- ticket valid 2 hours
- timed-entry tickets required
- two light sources required
Photos
