Trail 239 down APE CAVE. lava tube is lower longest. Between Swift Creek Reservoir & S tip of Mt St Helens Park. St Rd 503 & Nat Forest Rd Closest town is Cougar, WA. Upper Cave is more challenging, but it has a skylite, and is not a dead end.
Explore the longest, continuous lava tube in the US. Washington State’s Ape Cave -- a popular hiking destination with spectacular views of Mt. Helens – was formed from volcanoes of the Cascade Mountain Range in western North America.
St Helens- WA----on Trail of Two Forests in the Mt. Helens region of South Cascades. "This particular cave is a lava tube formed 1950 years ago during an eruption when lava flowed from fissures on Mount St.