Looking for an adventure? Explore a mountain inside and out. Twist and bend through underground marble passages on a ranger-guided tour of the Oregon Caves, deep in the Siskiyou Mountains. Wonder at the smooth wet growths of stalactites and stalagmites. Gaze into the Wild and Scenic River Styx — the first and only underground river in the National System — as it flows beneath your feet. Above ground, you can hike old growth forests and high mountain meadows, or relax inside the Chateau at the Oregon Caves, a National Historic Landmark. Cave tours run late March through early November.