A lava tube on the south flank of Mount St. Helens carrying more than two miles of passage under the forest, and the Forest Service description of it is refreshingly blunt: chilly, and pitch black. A short paved trail leads in beneath big trees to a stairwell that drops into the cave, so the entrance end is accessible to anyone. What waits below is genuine caving rather than a stroll. Bring two light sources and preferably a third, because the dark in a lava tube is absolute, with no daylight leaking in behind you to walk back towards. It is open May 18 to October 31, 9 a.m. to 5 p.m., and closed through the winter; in season you need a timed reservation from Recreation.gov and a $5 day-use pass per vehicle. The lower cave is an easy three-quarter mile, the upper runs a mile and a half with an eight-foot rock wall to climb, and a phone light is not enough. Pets, food and drinks other than water stay outside.
Other places on the map within a couple of hours.
