If you’re looking for a unique outdoor experience in the Pacific Northwest, Ape Cave offers something you won’t find on a typical hiking trail. Located on the southern flank of Mount St. Helens, this fascinating lava tube cave lets you step inside the volcanic forces that shaped the region. Whether you’re a seasoned hiker or just curious about underground landscapes, exploring ape cave is an unforgettable adventure.
What Is Ape Cave?
Ape Cave is one of the longest lava tube caves in North America, stretching roughly 2.5 miles beneath the surface. Unlike limestone caves filled with stalactites and stalagmites, this cave was formed by flowing lava about 2,000 years ago. As molten rock moved downhill during an eruption of Mount St. Helens, the outer layer cooled and hardened while the inside continued to flow. Once the lava drained away, it left behind a hollow tunnel—what we now call Ape Cave.
Walking through Ape Cave feels more like hiking through a rugged, rocky corridor than exploring a traditional cave. The walls are dark basalt, the floor is uneven, and the entire experience is shaped by ancient volcanic activity.
The History Behind Ape Cave
Despite its name, Ape Cave has nothing to do with primates. It was discovered in the mid-20th century by a group of local explorers known as the “Mount St. Helens Apes.” This adventurous club spent time studying and mapping caves in the area, and their nickname eventually stuck to this lava tube.
Over time, Ape Cave became one of the most popular attractions in the Gifford Pinchot National Forest. Its accessibility and unique geology draw thousands of visitors each year. Today, it’s managed by the U.S. Forest Service, which helps preserve the cave while allowing people to safely explore it.
The cave also sits within a landscape shaped by the dramatic 1980 eruption of Mount St. Helens. While ape cave itself predates that eruption by centuries, visiting the area gives you a deeper appreciation of the volcano’s ongoing influence.
Best Season to Visit Ape Cave
Timing your trip to ape cave can make a big difference in your experience. The cave itself stays at a constant temperature of about 42°F (5–6°C) year-round, but the conditions outside vary significantly.
Late spring through early fall (May–October) is the best time to visit. During these months:
- Roads leading to the cave are typically open and clear of snow
- Trail conditions are safer and easier to navigate
- Daylight hours are longer, giving you more time to explore
In winter, heavy snowfall can block access roads, making it difficult or impossible to reach the cave without specialized equipment. Even if you do make it, icy conditions can make the hike more hazardous.
If you want fewer crowds, consider visiting on a weekday or early in the morning during peak summer months.
What to Expect Inside Ape Cave
Ape cave is divided into two main sections:
Lower Cave (Easy Route):
- About 0.75 miles one way
- Mostly flat and family-friendly
- You return the same way you entered
Upper Cave (Challenging Route):
- Roughly 1.5 miles one way
- Includes scrambling over rocks and an 8-foot lava fall
- Ends at a forest exit trail above ground
The upper route is the more adventurous option and gives you a better sense of the cave’s scale and geological features. However, it requires good balance and moderate fitness.
No matter which route you choose, expect total darkness once you’re inside. There is no natural light beyond the entrance, so proper gear is essential.
Tips for Exploring Ape Cave
Exploring ape cave is exciting, but preparation is key. Here are some practical tips to make your trip safe and enjoyable:
- Check the website
Before your visit, check their website for current conditions. - Bring multiple light sources
Each person should carry at least two reliable light sources, such as headlamps or flashlights. The cave is pitch black, and a backup is crucial. - Dress warmly
Even on a hot summer day, the cave remains cold. Wear layers, including a jacket and sturdy pants. - Wear proper footwear
The cave floor is uneven and rocky. Hiking boots with good traction will help prevent slips and ankle injuries. - Watch your footing
Loose rocks and lava formations can be tricky. Take your time, especially in the upper cave. - Respect the environment
Avoid touching cave walls unnecessarily and never leave trash behind. The ecosystem inside is fragile. - Protect wildlife
Bats inhabit the cave, and they are vulnerable to diseases like White-Nose Syndrome. Avoid bringing gear used in other caves to prevent contamination. - Know your limits
If you’re unsure about climbing or navigating rough terrain, stick to the lower cave.
Driving Directions to Ape Cave
Getting to Ape Cave is part of the adventure. Here are step-by-step directions if you’re driving from the Portland area:
- Start by heading north on I-5 toward Washington.
- Take Exit 21 for Woodland and turn right onto WA-503 East (Lewis River Road).
- Continue on WA-503 for about 30 miles, passing through small towns and forested areas.
- Follow signs toward Mount St. Helens National Volcanic Monument.
- Turn right onto Forest Road 90 and continue driving.
- Turn left onto Forest Road 83 and follow it for several miles.
- Watch for signs directing you to Ape Cave and turn onto Forest Road 8303.
- Continue to the Ape Cave parking area at the end of the road.
Road conditions can vary, so check ahead for closures or maintenance updates, especially outside the summer season.
Why Ape Cave Is Worth Exploring
Ape cave offers a rare chance to walk through a volcanic formation that tells the story of Earth’s dynamic processes. Unlike scenic viewpoints or traditional hikes, this experience immerses you in the aftermath of an eruption—literally beneath the surface.
From its fascinating history to its cool, dark interior, ape cave is both educational and adventurous. Whether you’re climbing through the upper tunnel or taking a relaxed walk in the lower section, the experience leaves a lasting impression.
After Exploring Ape Cave
If you have extra time while exploring Ape Cave, consider adding a short side trip to Dead Horse Cave. Located within the Gifford Pinchot National Forest, this lesser-known lava tube offers a quieter, more rugged alternative with far fewer visitors. One of its most notorious features is the “Masochist Maze,” a tight, twisting section of narrow passages that require crawling, squeezing, and a good tolerance for confined spaces—definitely not for the claustrophobic. Dead Horse Cave is less developed than Ape Cave, so expect uneven terrain, minimal signage, and a greater need for navigation skills, reliable lighting, and sturdy footwear. For adventurous visitors, it’s a thrilling way to experience a more raw and challenging side of the volcanic landscape shaped by Mount St. Helens.