Wadi Mujib is a deep gorge in the Jordanian plateau, cut by the Mujib river on its way to the Dead Sea. The King's Highway crosses it on a dramatic descent, dropping from the high farmland of Moab down into the canyon and climbing out again on the far side, and the change of altitude is striking. The gorge is about four kilometres wide at the top and the floor lies close to the level of the Dead Sea, one of the lowest places on Earth. In the Bible this canyon was known as the Arnon, and it marked the border of Moab.
The riding is memorable rather than technical. The road swings down in long bends and hairpins, with views across the red, orange and ochre rock layers, and then climbs back up in the same way. Traffic includes trucks and tourist buses, so overtaking needs care, and the surface can be patchy after winter rain. Wind can be strong on the exposed sides. Heat is the main issue in summer, and the descent into the canyon feels like entering an oven.
Wadi Mujib is also a nature reserve, the lowest in the world, and its sandstone canyon holds a permanent river fed by springs and side streams. Ibex live in the cliffs, and the reserve has a good variety of birds and plants. Visitors can walk or wade in the water-filled gorge in season, with a guide and a permit from the reserve, but the river can flood suddenly after rain upstream, so it is not a place to wander without information.
There are no towns right at the gorge, so fuel and food are a matter of planning. The nearest sizeable town is Karak, known for its Crusader castle, about thirty kilometres south. Smaller villages like Ar Rabbah and Al Qasr are nearer but have limited services. Fill the tank before descending, carry water, and bring sun protection.
Stop at the viewpoint above the dam if you can. The scale of the canyon, and the thin line of road clinging to its walls, is easier to appreciate from a distance than from the saddle.