Approached from the north, the Victoria Falls announce themselves as a cloud of vapour hurled, grumbling loudly at its own immensity, into the African sky. A local tribe gave the falls the name Mosi-oa-Tunya - 'The smoke that thunders'.
Soaring 1600ft (500m) high, the misty plumes - which are visible from about 25 miles (40km) away - signal an unwary river's Magnificent catastrophe. As it moves towards them, the great Zambezi River is serene and mature, with only a scattering of islands to trouble its somnolent flow.
Nothing in the surrounding landscape - undulating, tree-scattered grassland on the Zambia-Zimbabwe border - or in the river's stately progress hints at the drama to come. Peaceful and 1 mile (1.6km) wide here in mid-course, the Zambezi abruptly plunges over a rock edge and changes in character completely.
Riven from bank to bank, the water drops in long sheets that seethe and roar in unimaginable fury as they cascade into a narrow, rocky, steep-sided chasm that reduces the river's width to a mere 65yds (60m). The spectacle is truly astonishing. Although the volume of water varies according to the season, rains can cause the swollen river to tip 540, 000 tons (550 million litres) a minute over the mile-wide rock rim - the world's widest sheet of falling water.
At Danger Point, a cliff ledge on the opposite side of the chasm, the downpour causes such an uprush of spray-soaked air that it can carry visitors' handkerchiefs skyward with the famous plumes of mist.
Brilliant rainbows are created as the sun's rays are refracted through drops of water in the air. Upthrusting rocks and islands decide the great front of falling water into three main sections, and one of them, the Rainbow Falls, takes its name from this effect (the other two are the Main Falls and the Eastern Cataract). And on a bright, moonlight night, the veil of vapour creates an unusual lunar window.
Along the cliffs facing the falls, there is luxurious woodland that is green all year round, in spite of the bleaching effect of the dry season on the surrounding grassland. This woodland, known as the rain forest, owes its verdancy to the moist microclimate created by spray from the cascade.
Downstream the grandeur continues as the entire volume of the river plunges into the narrow gorge and hurtles in all its wild glory towards a swirling pool called the Boiling pot. Beyond, it continues through zigzag gorges for more than 40 miles.