The Subway Zion
The Subway is a classic semi-technical slot canyon hike in Zion National Park. To complete the hike you wade/swim/scramble/climb down the Left Fork of North Creek. The stream is the trail for most of the route. Some of the holes are deep enough that you do have to swim, and the water is cold.
The hike is somewhat like the famous Narrows, only more intense. You climb down waterfalls and scramble over boulders. Serious rappelling is not necessary but ropes come in handy to help get people over cliffs and to lower packs.
Most canyoneers do this canyon from top down - it is very difficult to do it bottom up. A shuttle is required. You must have a permit to hike this canyon; permits can be obtained at any Visitor Center. Get detailed trail information before doing this hike. Only attempt this canyon if you are hiking with an experienced canyoneer.
Wildcat Trailhead(37.339954, -113.075776)
Begin the hike at the Wildcat Trailhead, on the Kolob Reservoir Road about 15.3 miles above the town of Virgin. Drinking water is not available at the trailhead.
Confluence Left Fork-Russell Gulch(37.317706, -113.040009)
During the first part of the hike you stay on top of ridges and cross shallow washes, until you reach the of Left Fork Canyon and Russell Creek. That's where you scramble down the steep hillside into the slot. Once in the slot you just hike downstream, finding ways over or around obstacles.
Subway Lower End(37.309656, -113.052595)
The semi-technical part of the route ends at the bottom of the Subway (at a spectacular small waterfall where canyon walls arch overhead and almost close to create a tunnel-effect - a subway). From there you continue hiking downstream past a large boulder covered with dinosaur tracks.
Exit Point(37.28944, -113.084722)
Exit the canyon where you see a sign marking the trail up the ridge to the Left Fork Trailhead. It is a steep, hot climb out of the canyon.
Left Fork Trailhead(37.284666, -113.095813)
The Left Fork Trailhead is signed and is about 8.1 miles above Virgin. That is where your shuttle should be waiting.