Ape Cave near Mt St Helens National Volcanic Monument park

Ape Cave is a fun and unique introduction to spelunking. The total length traveled is almost three miles long, with the lower level an easy walk and the upper level involving more boulder scrambling and an occasional wall climb. Good lights, food, water, and warm clothes (no matter how hot it is outside) are all highly recommended.

The cave is formed by a long lava tube. Long ago, lava flowed through an underground passage and eventually drained out below, leaving an open cylindrical cave behind. The cave has three places along its length that vent to the outside, two of which are set up for entrance or exit by visitors.

The best way to explore Ape Cave is to drive to the Main Entrance, which is located on the south side of Mt St Helens Volcanic National Monument park in Gifford Pinchot National Forest. This entrance to the interpretive site places you about 1/3 of the way along the tunnel from its lowest point. From there, travel down the easy and gradual descent to the lower end, turn around, come back and pass the Main Entrance, and then continue upwards for the remaining 2/3 of the cave all the way to the Upper Entrance. From there, a hiking trail leads back to the initial parking area.

This is definitely a fun one!