Grand Prismatic Overlook - The Rainbow From Above

A stop on Yellowstone Geyser Country, a free self-guided tour.

From this hillside platform you see what the boardwalk below can't show you: Grand Prismatic Spring laid out like a giant eye, a deep blue center ringed by bands of yellow, orange and red that bleed out across the basin.

The spring is about 370 feet across, wider than a football field is long, and about 160 feet deep. Members of the 1871 Hayden survey named it for its rainbow of colors. The blue comes from the water itself, deep, clear and too hot for most life. The bright rings are microbial mats, communities of heat-loving bacteria and archaea. Each color marks a different temperature zone, and the oranges and reds are richest in summer.

The walk here is about 0.6 miles each way from the Fairy Falls Trailhead, climbing gently about 105 feet. Bison often graze this flat, so give them at least 25 yards, and bears and wolves at least 100. Bring water and sun protection; there's little shade on the trail.

Getting here: Drive north about 2 miles from Biscuit Basin to the Fairy Falls Trailhead lot, a mile south of Midway Geyser Basin, then walk the trail across the Firehole River and take the signed spur up to the platform.

Did you know?: In 1839, fur trappers described what was probably this spring as a boiling lake about 300 feet across.

Photo op: Late morning on a warm, sunny day gives the clearest view once the steam thins; a wide lens catches the whole spring, and a zoom picks out boardwalk visitors for scale.

Nearby: Parking at the Fairy Falls Trailhead is very limited, so arrive early; there's no food or water. Restrooms and more parking are at Midway Geyser Basin just up the road.

More on Wikipedia: Grand Prismatic Spring · Ferdinand Vandeveer Hayden

Grand Prismatic Overlook - The Rainbow From Above

Stops on this tour