Box Canyon, in Mt. Rainier National Park is very aptly named since it a geographical box canyon or a small ravine or canyon with steep walls on three sides and follows a zigzag course allowing access only through the mouth of the canyon. It is very unusual to have such a narrow, deep and steep walled canyon in a glaciated area. More typical are the huge U-shaped canyons like Stevens Canyon which was carved out of glaciers.
This canyon is located roughly halfway between Longmire and the Stevens Canyon Park Entrance and is open for access June to September depending upon snow melt. A .3 mile one-way mostly paved trail leads across a canyon bridge and down along the canyon and eventually splits off from the Wonderland Trail.
Just looking down at the narrow walls covered in green mosses, trees clinging precariously to the edge and smooth basalt while the river pulses down through the canyon is worth the one hour side trip.
Please feel free to add your own pictures if you have visited this amazing place.