Victoria Falls a visa each time they cross the border; visas can be obtained at both border posts. Costs vary from US$50–$80 (). Visa regulations change frequently; visitors are advised to check the rules currently in effect in both countries before crossing the border in either direction. Additionally, foreign tourists may purchase a KAZA visa for US$50 that will permit visitors to travel between Zambia and Zimbabwe for up to 30 days as long as they remain within the covered countries. A famous feature is the naturally formed "Armchair" (now sometimes called "Devil's Pool"), near the edge of the falls on Livingstone
Victoria Falls is roughly twice the height of North America's Niagara Falls and well over twice the width of its Horseshoe Falls. In height and width Victoria Falls is rivalled only by Argentina and Brazil's Iguazu Falls. See table for comparisons. For a considerable distance upstream from 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; only a flat plateau extending hundreds