Victoria Falls waterfall, c.1 mi (1.6 km) wide with a maximum drop of 420 ft (128 m), in the Zambezi River, S central Africa, on the Zambia-Zimbabwe border. The falls are formed as theZambezi plummets into a narrow chasm (c.400 ft/120 m wide) carved by its waters along a fracture zone in the earth's crust. Numerous islets at the crest of the falls divide the water to form a series of falls. The thick mist and loud roar produced there are perceptible from a distance of about 25 mi (40 km). The Boiling Pot, the beginning of a winding gorge (c.50 mi/80 km long) through which the river flows below the falls, is spanned by a 650 ft (198 m) long bridge that is 310 ft (94 m) above the river. The gorge is now partially submerged as a result of the construction of the Kariba Dam . DavidLivingstone , the British explorer, visited the falls in 1855 and named them for Queen Victoria. The falls are part of two national parks and draw many tourists to the area.