Explore one of North America's longest lava tubes inside Gifford Pinchot National Forest. This 2.5-mile cave, carved by ancient lava flows, offers two distinct routes: the easy, family-friendly Lower Cave (3/4 mile) and the more adventurous Upper Cave (1.5 miles) with an 8-foot wall climb and rock scrambles. Constant 42°F temperatures year-round make it a refreshing escape, but you'll want two light sources and warm layers. Timed-entry reservations are required in season via Recreation.gov. Whether you're a first-time caver or a seasoned explorer, Ape Cave delivers a unique underground adventure.
Best season — Summer to early fall (July–October) for dry conditions; cave open year-round but may be icy in winter.
At a glance
The facts worth checking before you roll out
Conservative, source-minded facts for planning your visit — always worth confirming against current conditions before you travel.
Managing agency
Gifford Pinchot National Forest, U.S. Forest Service (USDA)
Cave type & length
Lava tube; ~2.5 miles long — among the longest lava tubes in North America
Routes
Lower Cave ~3/4 mi (easy, family-friendly); Upper Cave ~1.5 mi (8-ft wall climb + rock scrambles)
Access
Timed-entry reservations required in season via recreation.gov; constant ~42°F year-round, bring 2 light sources + warm layers
On the ground
Ape Cave is a lava tube within Gifford Pinchot National Forest, notable as one of North America’s longest. Formed by ancient lava flows, the cave presents a unique underground experience for visitors. Two routes are available: an easier 3/4-mile Lower Cave and a more strenuous 1.5-mile Upper Cave with physical challenges.
RV travelers visiting Ape Cave can choose between exploring the family-friendly Lower Cave or tackling the adventurous Upper Cave, which includes an eight-foot wall climb and rock scrambles. Regardless of route selection, all visitors should be prepared for uneven terrain inside the cave; no developed trails exist within the lava tube itself.
The best time to visit is summer through early fall, when drier conditions prevail. Ape Cave remains open year-round, though icy conditions may occur during winter months. Timed-entry reservations are required in season and can be secured through Recreation.gov for access to this popular site.
Consider establishing a basecamp somewhere nearby the Mount St. Helens area to allow flexible exploration of Ape Cave and other regional attractions. Remember that the cave maintains a constant 42°F temperature, so pack warm layers along with two independent light sources per person for any time of year.
Official sources
- U.S. Forest Service — Ape Cave USDA Forest Service
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