The importance of wildlife protection in Botswana cannot be overstated. The success of the tourism industry in the country rests heavily on its wildlife. The country's wildlife estate makes up more than one-third of its landmass, with its national parks and game reserves comprising 17% of the estate and its wildlife management area encompassing over 20%. Okavango Delta, which is the largest inland wetland habitat in the world, is said to be the biggest draw for tourists that visit the country. About 90% of all visitors of the country come for "a wildlife and wilderness-based vacation" and revenue from tourism accounts for 12% of the country's gross domestic product.