Access to the Grand Prismatic Spring is included in Yellowstone's seven-day pass ($35) and there are no set hours of operation. Park rangers suggest caution around the hot springs by staying on ...

The beating heart of Yellowstone National Park is without a doubt the Grand Prismatic Spring—the largest hot spring in the U.S. Its colorful bands are the product of hardy bacteria and algae ...

If visitors look closely, they’ll see small black creatures hunting and scavenging in and around the springs — a stunning feat of survival, given the high temperatures.  These are wetsalts tiger ...

Located in Wyoming this national park sits atop a giant supervolcano, with a newly discovered volcanic vent emitting steam ...

Yellowstone National Park is a place where steam rises from the earth and geysers erupt like clockwork. Parameters were ...

Yellowstone National Park's nearly 3,500 square miles seep ... the Old Faithful area is home to Old Faithful and the Grand Prismatic Spring, two of Yellowstone's most famous attractions.

Editor’s Note: This story accompanies the May 2016 issue of National Geographic magazine, devoted entirely to America’s first national park. Find more at natgeo ...