Dark Canyon is an amazing place and is now included in the newly-formed Bears Ears National Monument. The Hayduke Trail travels a portion of the canyon from the junction with Youngs Canyon to the Sundance Trail exit.
There are no major obstacles in Dark Canyon, though travel down through the lower canyon (below Sundance Trail) includes a few sketchy ledges. Between Youngs and Sundance there are some route-finding challenges to avoid deep pools and then above Youngs is a minor obstacle for which there is an easy bypass on the south side.
Until I have time to do a full Hike Guide for this awesome place, here’s a gallery with captions instead: