黄石国家公园的大棱镜泉，怀俄明州 The Grand Prismatic Spring in Yellowstone National Park, Wyoming (© Martin Rügner/DEEPOL by plainpicture)

黄石国家公园的大棱镜泉，怀俄明州 The Grand Prismatic Spring in Yellowstone National Park, Wyoming (© Martin Rügner/DEEPOL by plainpicture)

Colors spring up in Yellowstone

As National Park Week continues, we're taking a look at the Grand Prismatic Spring, one of the more popular attractions in Yellowstone National Park. Visitors on an elevated wooden boardwalk come to witness the vivid colors, which are formed due to a cycle of hot water rising, cooling, and falling--creating rings of distinct temperatures inside the spring. The clear, blue center is the hottest part, with almost nothing living in it. But the other rings are home to different organisms that give the water its rings of color. While it's beautiful to look at, you wouldn't want to swim in it. It's illegal, but it's also much too hot—and the sulfur smell wouldn't leave you feeling too clean.