Across Australia, all walking routes are marked as being in one of six different classes. Classes 1–3 can be completed comfortably by most, Class 4 requires a reasonable level of fitness, while Class 5 tend to be exhilarating semi-Indiana Jones-style adventures. Class 6 requires you to either be a qualified rock-climber and abseiler with all the necessary equipment, or on a guided tour.
While lesser trails are not uniformly well marked, the “Trail Risk” signs certainly are, and will warn you if you’re about to venture into a Class 6 area. Injuries are common in Karijini National Park, and fatalities do occur, so think carefully about which trail your level of fitness will allow you to complete comfortably, and wear solid walking sandals – on many walks a small slip could see you plunge a fair distance down a gorge face.