After watching Old Faithful erupt we went to the visitors center located there and then headed back on the road. Our next stop was the Great Prismatic Spring. The Great Prismatic Spring is the largest hot spring in the United States and the third largest hot springs in the world. It discharges 560 gallons every minute and the temperature of the water is 160 degrees. There is a wooden boardwalk that takes you out to it. It was a cool morning but when you get out there on the boardwalk near the spring you go from feeling chilly to hot when the steam hits you- then cool again a second later after it passes. A very strong sulfur smell out there also.