Wadi Mujib is the lowest nature reserve on Earth, and the Kings Highway crosses it in one of the most dramatic descents in Jordan. The road drops from the plateau near Madaba down the side of a great canyon, in a long series of bends, to a bridge at the bottom, and then climbs the other side, a change of several hundred metres in a few kilometres. The canyon, which the Bible calls the Arnon, was the boundary between the kingdoms of Moab and the Amorites, and it carves a deep red-brown gash through the sandstone toward the Dead Sea.
The Mujib river runs year-round, flowing out through a narrow gorge into the Dead Sea, whose shore lies around 430 metres below sea level, the lowest land on Earth and falling still. The reserve, run by Jordan's nature society, protects a remarkable range of habitats, from desert slopes to palm-lined pools, and is home to Nubian ibex, hyrax, foxes and many birds. The walking trails through the water-filled gorge are famous, but they are strictly managed, closed in the wet season when flash floods can kill, and need booking in advance.
The riding here is a joy. The Kings Highway is an old route, mentioned in the Book of Numbers, and the modern road follows it along the edge of the plateau, with wide views, tight hairpins and little traffic. The surface is generally good, but there can be sand, gravel and the occasional goat on the road, and the wind is strong on the exposed sections. Heat is the main issue: summer temperatures at the bottom of the gorge can exceed forty degrees, so carry plenty of water and wear ventilated gear. Spring and autumn are far kinder.
Dhiban, on the plateau to the south, is where in the nineteenth century a black basalt stone was found bearing an inscription by Mesha, king of Moab, the earliest known text to mention the God of Israel outside the Bible. Fuel is a practical concern: the nearest big town is Madaba, twenty-eight kilometres away, and a few small stations lie on the road, so fill up before the descent. Simple cafes by the roadside serve strong tea and fresh bread. The best seasons are March to May and October to November, when the light on the canyon walls is glorious.