Gringo Trails: Is tourism destroying the world?

By Zoe Li, for CNNUpdated 3rd January 2014
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Pegi Vail (left) and Melvin Estrella, "Gringo Trails" cinematographer and co-producer respectively, shooting on the Bolivian salt flats.
Pegi Vail (left) and Melvin Estrella, "Gringo Trails" cinematographer and co-producer respectively, shooting on the Bolivian salt flats.
Courtesy Pegi Vail
Tourism hangover: Koh Pha Ngan beach after full moon party.
Tourism hangover: Koh Pha Ngan beach after full moon party.
Courtesy Pegi Vail
Dangerous territory: Should illegal Mexican +border crossings be recreated for tourists?
Dangerous territory: Should illegal Mexican +border crossings be recreated for tourists?
John Moore/Getty Images