1 Best Sight in Washington Cascade Mountains and Valleys, Washington

Ape Cave

Measuring nearly 2½ miles in mapped length, Ape Cave is the longest continuous lava tube in the continental United States. Two routes traverse the tube: the lower route is an easy hour-long hike, while the upper route is more challenging and takes about three hours. Bring at least two light sources (you can rent lanterns from the headquarters for $5 in summer) and warm clothing. In high season ranger-led walks are sometimes available; inquire at the Apes' Headquarters, off Forest Service Road 8303, three miles north of the junction of Forest Roads 83 and 90. Although Ape Cave is open year-round, the headquarters closes November through April. A Northwest Forest Pass ($5 daily) is required for parking (or a Sno-Park permit during winter).