Tourists visit the Jiuzhaigou Valley, a World Heritage site famous for its colorful pools and snowy mountains, in southwest China's Sichuan Province, Oct. 26, 2015. (Xinhua/Wang Song)

Tourists visit the Jiuzhaigou Valley, a World Heritage site famous for its colorful pools and snowy mountains, in southwest China's Sichuan Province, Oct. 26, 2015. (Xinhua/Wang Song)

Tourists pose for photos at the Jiuzhaigou Valley, a World Heritage site famous for its colorful pools and snowy mountains, in southwest China's Sichuan Province, Oct. 26, 2015. (Xinhua/Wang Song)

Tourists visit the Huanglong scenic spot, a World Heritage site famous for its colorful pools and snowy mountains, in southwest China's Sichuan Province, Oct. 25, 2015. (Xinhua/Wang Song)

Tourists take photos at the Huanglong scenic spot, a World Heritage site famous for its colorful pools and snowy mountains, in southwest China's Sichuan Province, Oct. 25, 2015. (Xinhua/Wang Song)

Tourists visit the Jiuzhaigou Valley, a World Heritage site famous for its colorful pools and snowy mountains, in southwest China's Sichuan Province, Oct. 26, 2015. (Xinhua/Wang Song)

Tourists visit the Jiuzhaigou Valley, a World Heritage site famous for its colorful pools and snowy mountains, in southwest China's Sichuan Province, Oct. 26, 2015. (Xinhua/Wang Song)

Tourists visit the Jiuzhaigou Valley, a World Heritage site famous for its colorful pools and snowy mountains, in southwest China's Sichuan Province, Oct. 26, 2015. (Xinhua/Wang Song)

Tourists visit the Jiuzhaigou Valley, a World Heritage site famous for its colorful pools and snowy mountains, in southwest China's Sichuan Province, Oct. 26, 2015. (Xinhua/Wang Song)

A tourist wearing Tibetan clothing poses for photos at the Jiuzhaigou Valley, a World Heritage site famous for its colorful pools and snowy mountains, in southwest China's Sichuan Province, Oct. 26, 2015. (Xinhua/Wang Song)