This area contains the most spectacular of the Hot Springs and is reached by crossing a bridge over the Firehole River. As you cross the bridge you can see the hot run off from the Excelsior Geyser as it falls over the edge into the river itself. Excelsior Geyser has not erupted since 1888 when it reached over 300 feet in height, over 5 million gallons of water, at 199 degrees Fahrenheit, boil forth daily from its gigantic crater. This water cascades through brilliant coloured run off channels and pours into the Firehole River This causes the river to erupt with steam.

As you climb the boardwalk you first pass Excelsior Geyser and the run off on your left. The boardwalk continues on along the edge of the fantastic Grand Prismatic Spring, which is Yellowstone’s and the world’s largest hot spring. A blue haze rises several feet above the water and the ring of bright orange and yellow algae and bacteria reach out like gigantic tentacles giving the appearance of a giant prism around the blue of the pool, which is 370 feet in diameter.