Morning Glory Pool is a hot spring in the Upper Geyser Basin of Yellowstone National Park in the United States. Its average temperature hovers around 157°F (69°C). The distinct color of the pool is a product of bacteria and on rare occasions it will erupt as a geyser, typically following an earthquake.
The Morning Glory Pool is right along the Firehole River, a few miles north of Old Faithful! You can simply take the paved path from the Visitor Center at Old Faithful and arrive there after about a mile and a half hike.