Sơn Trà Peninsula is a mountain of rainforest rising straight out of the city of Đà Nẵng on the central coast of Vietnam, 700 metres high and ringed by a coastal road, and it holds one of the largest troops in the world of the red-shanked douc, a langur with crimson legs and a white face, among the most colourful primates alive. The peninsula was a closed military zone through the war, which is why the forest survived while the coast below was built up, and it is a nature reserve now, ten minutes from the city's hotels; the doucs, more than a thousand of them, feed in the roadside canopy in the first hours after dawn, and the way to see them is to ride the Hoàng Sa road slowly with the engine off at the bends, scanning the treetops for a flash of red legs and a pale face among the leaves, with the sea behind. The road switchbacks up from the shore into the forest, each hairpin opening on a turquoise cove or a long drop to Đà Nẵng bay, and drops to small sand coves at the foot of the trees, Bãi Bắc and Bãi Rạng among them, where the swimming is off the rocks.
At the southern foot of the mountain stands the Lady Buddha of Linh Ứng pagoda, a white statue of the goddess of mercy 67 metres tall, the tallest in Vietnam, gazing out to sea and dwarfing the pilgrims below. Near the peninsula's southeastern tip a banyan thought to be about 800 years old holds its crown aloft on a tangle of aerial roots, and on the seaward cliffs the headland track leads to the old Tiên Sa lighthouse, where the forest gives way to rock and open water. The doucs may be the mountain's best protection, since the monkeys are a large part of why the reserve has held off the resorts eyeing its shore. Sơn Trà is a forest a city kept, and the red-legged monkeys are its argument.