Ape Cave - Mount St Helens National Monument

Ape Cave is a lava tube on the south side of Mount St. Helens that anyone with a flashlight can go hike and explore. Unlike a cave system, the tube only goes one direction so you are not going to get lost. Ape Cave is the most popular attraction inside the National Monument and the longest lava tube in the continental United States at over two miles in length.

A short paved trail takes you from the parking area to the cave entrance. A few sets of stairs take you to the bottom. At that spot is a sign. You can choose to do the lower or upper cave. The lower cave goes 3/4 mile and dead ends. It is easy walking and the one suggested for anyone who might have trouble walking over rocks. The other direction is the upper cave. It is 1.5 miles long and has an exit. You then walk a trail on the surface back to the parking area. This upper cave has more difficult walking. Areas of boulders and rocks must be scrambled over. People accustomed to trail hiking won't have any problems. There is one 8-foot high lava fall as well which must be climbed over. The park service suggests 2+ hours to complete but this is really conservative. Just be sure to have 2 or 3 sources of light, you would have to wait for another party to come along if your light went out. But, given the popularity of Ape Cave, that may not be to long.

Ape Cave was formed around 2,000 years ago when lava poured down
the southern flank of Mount St. Helens. As the lava flowed, the outer
edges of the lava stream cooled forming a hardened crust which insulated the molten lava beneath. This allowed the lava to remain hot and fluid encased in the lava tube.

Local lore says the name of Ape Cave came from a scout troop who explored the caves back in the early 50s. The troops sponsor was the St. Helens Apes, a group of foresters. Foresters and loggers in those days were sometimes referred to as Brush Apes.

Ape Cave - Mount St. Helens Monument