A. A permit issued by Zion is required to enter the Subway. There are two ways to experience this trail: Top-Down and Bottom-Up.  Top-Down is a canyoneering route that requires knowledge and experience, as well as the gear for it. It is a dangerous trail without that skill set and should not be attempted unless accompanied by someone who knows what they are doing. Water levels in the slot canyon fluctuate throughout the year but several deeper pools of water are usually present and require you to fully submerse in water. Dry bags are recommended to protect valuables like cameras and phones. The route begins at the Wildcat Canyon Trailhead and exits at the Left Fork Trailhead. Bottom-Up is far less technical, and only requires hiking and scrambling skills. There are lots of boulders to navigate and the trail can be extremely uneven and broken up in the bottom half. The trail follows the creek in the bottom of a steep ravine and crisscrosses the creek many times. Water levels in the creek fluctuate throughout the year but generally you should only have to get wet from the knees down. The route begins and ends at the Left Fork Trailhead.