Yellowstone National Park (4) - Grand Prismatic Spring

Grand Prismatic Spring at Yellowstone’s Midway Geyser Basin
the Grand Prismatic Hot Spring is the most photographed thermal feature in Yellowstone. That's because of its crazy-bright colors and enormous size.

Excelsior Geyser Crater
Today, this steaming, bright blue pool is essentially a hot spring. But in its heyday in the late 1800s, Excelsior erupted to heights of about 300 feet. It went dormant for much of the 20th century, only to suddenly erupt for two days in 1985—some of its blasts reached 80 feet in height. Though it’s a quiet pool now, Yellowstone’s constantly changing thermal landscape could revive Excelsior Geyser to its former glory once again.

Yellowstone’s Midway Geyser Basin may be small, but it packs a big punch: In addition to Grand Prismatic Spring, see Excelsior Geyser, an enormous geyser crater, Turquoise Pool, and Opal Pool. You can get up close by strolling across the Firehole River and along the short boardwalk that snakes through the thermal area. Be sure to stay on the boardwalk. It is illegal and very dangerous to walk in the geyser basin.