Botswana's Okavango Delta is the second largest inland river delta in the world, after the Niger Inland Delta, and represents one of the most unusual ecosystems on the planet. It is formed by the Okavango River, which has its source in Angola (near Huambo) and reaches its mouth after a journey of over 1000 km and meeting numerous tributaries. This extraordinary environment gives life, on the edge of the desert, to an exuberant fauna and flora, and has attracted numerous human settlements (five different ethnic groups live near the delta).