Africa's Victoria Falls or Mosi-oa-Tunya (the smoke that thunders) are, by some measures, the largest waterfall on the planet, as well as being among the most unusual in form, and having arguably the most diverse and easily-seen wildlife of any major waterfall site.
Although Victoria Falls constitute neither the highest nor the widest waterfall in the world, their claim to be the largest is based on a width of 1.7 km (1 mile) and height of 108 m (360 ft), forming the largest sheet of falling water in the world. The falls' maximum flow rate compares well with that of other major waterfalls (see table below).
The unusual form of Victoria Falls enables virtually the whole width of the falls to be viewed face-on, at the same level as the top, from as close as 60 m (200 ft), because the whole Zambezi River drops into a deep, narrow slot-like chasm, connected to a long series of gorges. Few other waterfalls allow such a close approach on foot.
Many of Africa's animals and birds can be seen in the immediate vicinity of Victoria Falls, and the continent's range of river fish is also well represented in the Zambezi, enabling wildlife viewing and sport fishing to be combined with sightseeing.
Victoria Falls are one of Africa's major tourist attractions, and are a UNESCO World Heritage Site (see box below). The falls are shared between Zambia and Zimbabwe, and each country has a national park to protect them and a town serving as a tourism centre: Mosi-oa-Tunya National Park and Livingstone in Zambia, and Victoria Falls National Park and the town of Victoria Falls in Zimbabwe.
For a considerable distance above the falls, the Zambezi flows over a level sheet of basalt, in a shallow valley bounded by low and distant sandstone hills. The river's course is dotted with numerous tree-covered islands, which increase in number as the river approaches the falls. There are no mountains, escarpments, or deep valleys which might be expected to create a waterfall, only flat plateau extending hundreds of kilometres in all directions.
The falls are formed as the full width of the river plummets in a single vertical drop into a chasm 60–120 m (200–400 ft) wide, carved by its waters along a fracture zone in the basalt plateau. The depth of the chasm, called the First Gorge, varies from 80 m (262 ft) at its western end to 108 m (360 ft) in the centre. The only outlet to the First Gorge is a 110 m (360 ft) wide gap about two-thirds of the way across the width of the falls from the western end, through which the whole volume of the river pours into the Victoria Falls gorges.
There are two islands on the crest of the falls that are large enough to divide the curtain of water even at full flood: Boaruka Island (or Cataract Island) near the western bank, and Livingstone Island near the middle. At less than full flood, additional islets divide the curtain of water into separate parallel streams. The main streams are named, in order from from Zimbabwe (west) to Zambia (east): Leaping Water (called Devil's Cataract by some), Main Falls, Rainbow Falls (the highest) and the Eastern Cataract. Wikipedia
