Hell Canyon was a 6.13 mile, loop trail near Custer, South Dakota. Generally considered a moderately challenging route, it took us 3 hours and 20 minutes to complete. This is a popular trail for hiking, but you can still enjoy some solitude during quieter times of the day. The trail is open year-round, but the best times to visit are June through October. Dogs are welcome and may be off-leash in some areas.