caves , glaciers , Glacier Bay National Park , the U.S. state of Alaska. 洞穴, 冰川

Power and beauty: Breathtaking images of ice caves deep beneath Alaska's glaciers | Mail Online http://www.dailymail.co.uk/news/article-2157643/Power-beauty-Breathtaking-images-ice-caves-deep-beneath-Alaskas-glaciers.html