The world's greatest oasis?

At a glance, this might look like some ordinary swamp, but the Okavango Delta in the African nation of Botswana is a veritable miracle of nature. Unlike most river deltas, the Okavango doesn't drain into any sea or ocean, but rather empties into the open savannah. This elephant, and just about every African animal you can name, owes its existence to this annual wetland. 'Annual,' because the marshland of the delta swells threefold to its full size but once a year, between March and July, when the seasonal rains from the highlands of Angola flow downhill 750 miles until they flood the arid savanna of northwest Botswana. The wildlife drawn to this life-sustaining water includes lions, leopards, cheetahs, rhinos, giraffes, zebras, hippos, wildebeests, hyenas, crocodiles, impalas, and of course elephants, the planet's largest land animals.
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