If you’re traveling overland across southern Africa, the vast waters of the Okavango Delta may come as a bit of a surprise. Like the outstretched palm of a hand, they fan out over northern Botswana—creating a patchwork of blue and green across the parched Kalahari sands. The Okavango is the world’s largest inland river delta. It is sprawling, expansive and wildlife-rich. The vast system of waterlogged marshes attracts a diverse array of birds and mammals. It is largely regarded as one of the best safari destinations in Africa.   THE…