Ape Cave — Mount St. Helens National Volcanic Monument

  • Forest Road 8303, 3 miles north Forest Roads 83/90 junction., Cougar, WA 98616
  • Visit Website

Over 2,000 years ago, lava poured down the southern flank of Mt. St. Helens.  As the hot lava flowed, the surface cooled, creating a crust, which insulated the lava beneath, allowing it to travel down the Lewis River Valley. The lava in the tube rose and fell as the eruption surged and slowed, contributing to the unique contours of the walls of this 2.47-mile lava tube. During this period, fluid lava pulsed through the tube for months, resulting in the third longest lava tube in North America.

Known as the Ape Cave at Mt. St. Helens National Volcanic Monument, visitors come from all over the world to view this natural phenomenon.  Dress warmly and bring at least two light sources, as quiet breezes slip past you at a constant 42 degrees as you descend into darkness of the cave. For the more adventurous, shut off your headlamp and experience a total absence of sound and light. Because of the unique location, the best months to visit the Ape Cave is June through October, as access is much easier without snow on roadways to the site.

  • Fee Required
  • Interpretive Signage
  • Trained Guides/Guided Tours/Self-Guided Tours Available
  • Visitor Center on Site (only open during June – October)

Sculpted by Water, Fire and Ice

The Central Cascades has seven themes that help to define the character of the region. This location is an example of Sculpted by Water, Fire and Ice. Here are more locations that exemplify this theme:

Get more information on this area from ExperienceWa.com

National Geographic