Step beneath the forest floor and discover one of the most unique adventures in the Mount St. Helens region. Ape Cave is a massive lava tube formed by ancient volcanic flows on the south side of Mount St. Helens, and at about 2.5 miles long, it is considered the third longest lava tube in North America. This unforgettable stop blends geology, adventure, and forest scenery into one of the area’s most memorable outdoor experiences.

The experience begins with a short paved path from the parking area to the cave entrance, where a stairway drops into a cool, dark underground world. From there, visitors can choose between two very different routes. The Lower Cave is the easier option, offering a relatively gentle out-and-back walk that is well suited for families and casual explorers. The Upper Cave is more challenging, with rocky footing, lava-formed obstacles, an 8-foot lava fall, and an exit ladder that brings you back to the surface for a forest hike to return to the main entrance.

Ape Cave is more than a hike. It is a chance to experience Mount St. Helens from the inside out. The cave stays around 42 degrees year-round, making it a refreshing summer adventure but one that requires preparation in every season. Visitors should bring warm layers and at least two reliable light sources per person, since there is no lighting inside the cave and cell phone flashlights are not considered adequate.

To help protect this fragile volcanic environment, visitors should avoid touching the cave walls or ceiling, and pets, smoking, camping, alcohol, and food or drinks other than water are not allowed inside. During the open season, timed entry reservations are required per vehicle, and parking also requires a Northwest Forest Pass, Interagency Pass, or day pass.

Whether you are looking for a family-friendly lava tube walk or a more adventurous underground scramble, Ape Cave offers a one-of-a-kind way to explore the volcanic story of Mount St. Helens. It is one of those places that feels equal parts trail, cave, and natural wonder.

Trail details: Ape Cave Trail #239, near Cougar, Washington. Main trailhead coordinates: 46.108645, -122.210387. The cave is reached via Forest Road 8303, roughly 9 miles east of Cougar.

Call to action: Add Ape Cave to your Mount St. Helens itinerary and experience one of the most unusual hikes in Washington, where volcanic history comes to life beneath your feet.

Current seasonal note: As of April 8, 2026, Ape Cave is in its winter closure period. The Forest Service page lists the site as seasonally closed from November 1 to May 17, while Recreation.gov currently says the 2026 summer season reopens on Friday, May 22 and requires timed tickets.

ALERT: COUGAR PARK and CAMPGROUND BOAT RAMP CLOSED UNTIL FURTHER NOTICE

• Day use and camping 
• Day use picnic area
• Swimming beach please note: for the safety of all swimmers, no personal floatation devices (including but not limited to: kayaks, paddleboards, inflatable watercraft, etc.)
  or use of oars or paddles are allowed within the swimming area
  
• Water and restrooms provided
• Boat ramp
  
• 45 tent camping only sites
• Group camping facility with 15 tent camping only sites and a covered picnic shelter with fireplace and sink
  
• Swimming beach
• Restrooms, showers and water provided
• Open the Friday before Memorial Day until Labor Day

**The Cougar Park boat launch on Yale Reservoir is also currently closed due to low water.
Beginning 9 a.m. Saturday, August 24, the boat launch at Beaver Bay Park on Yale Reservoir will also close due to low water until further notice.

Cresap Bay Campground Information

Open Friday before Memorial Day through September 30: 6 a.m. - 9 p.m.

•56 overnight campsites; make a campsite reservation
•Group camping facility with 15 campsites (group site has a covered shelter with a fireplace, sink and electricity)
•Day use and camping (see fees)

•Swimming beach
•Two-lane boat ramp

•Separate 23-slip marina available for first come, first served use by overnight guests at the campground

•Water, restrooms and showers provided
•Recreational vehicle dump station, but no RV hook-ups at campsites

•Entrance gate closes at 9 p.m.

Visitors entering day use sites via vehicles are required to pay applicable fees. Pass holders must check in with booth attendant (if staffed). Passes must be displayed in car window at all times. Fees are non-transferable.

The hotel at the Lone Fir Resort is a comfortable and peaceful getaway from the rigors of daily life. Stay a night, a week or more! Enjoy the quaint setting and rustic nature of the numerous rooms and cabins. The area offers day trip activities such as hiking, biking, fishing, boating and much more! A drive to view the grandeur of Mount St. Helens is always a refreshing trip for visitors to the area. All rooms & cabins have a private bathroom, a coffee maker with coffee, a microwave and a small refrigerator for your added convenience. Several rooms feature full kitchens. The Resort also consists of restrooms with showers, a cafe, a gift shop, and a swimming pool.

Conveniently located near Mt St Helens, and this Cougar, WA hotel is conveniently located to local attractions.
* Yale Reservoir
* Swift Reservoir
* Lewis River Falls

Mount Saint Helens is a short drive away
* SR 503 side of Mt St Helens (Lewis River Road is SR 503)
* Lava Canyon
* Ape Caves
* Trail of Two Forests
* June Lake
* Sno-Park Marble Mountain
* Climbers Bivouac Trailhead
* Windy Ridge