YELLOWSTONE NATIONAL PARK, UNITED STATES
The Grand Prismatic Spring, the largest in the United States and third largest in the world, and it's...
The Grand Prismatic Spring, the largest in the United States and third largest in the world, and it's colored bacteria and microbial mats in Yellowstone National Park, Wyoming, June 22, 2011. REUTERS/Jim Urquhart (UNITED STATES)