Tourists view the Morning Glory hot spring in the Upper Geyser Basin of Yellowstone National Park in Wyoming, on May 14, 2016. The distinctive colors of the hot spring is due to bacteria which survive in the hot water although its vivid color has changed from its original blue to yellow and green after an accumulation of coins and debris thrown by tourists. / AFP PHOTO / Mark Ralston (Photo credit should read MARK RALSTON/AFP/Getty Images)
