 Now, if the sun were shining, we'd have seen a kaleidoscope of blues and reds and yellows that ring the famous Excelsior geyser and the Grand Prismatic Spring. But at night, from this vantage point, you couldn't really see anything. You could only hear. That's the runoff from Excelsior geyser. Pouring out of a geyser crater into the Firehole River.