Distance: .75 mile (round trip)
Best time of year: Summer
Last hiked: 2015 September
The Midway Geyser Basin is definitely one of the crown jewels of roadside attractions in Yellowstone National Park (and its parking lot attests to that). It features two of the most spectacular features in the park: the Excelsior Geyser Crater and Grand Prismatic Spring, the latter being the third largest hot spring in the world and the largest in Yellowstone. Unfortunately, due to the heat from both of these features, this walk is really only worth doing on warmer days in the summer. Though open year-round, there’s simply too much steam on cooler days to really see what makes this stop so special. Also, if you’re wearing a hat, hold on to it. Winds along the boardwalk can be gusty and you’ll see evidence of others who weren’t expecting the gusts to sweep the hats off their heads. Since you’re required to stay on the boardwalk, consider it lost if it flies off.
From the parking area, head along the Firehole River to the bridge where you’ll get excellent views of the runoff from the scalding Excelsior Geyser Crater. It’s created its own small waterfalls pouring down the sinter cliffs into the river. From here, the boardwalk heads up the small hill and brings you back to the runoff of the geyser crater. Orange and yellow thermophiles line the water on the way to the thermal feature until the water is too hot from its source for them to survive. The Excelsior Geyser Crater is a massive, brilliant blue pool whose water is roughly 200 degrees Fahrenheit. This was previously one of the largest geysers in the park. In the late 1800s, eruptions shot out up to 300 feet high, and just as wide. Because the eruptions were so large and violent, it ultimately blew itself apart, releasing the pressure that caused such dramatic displays. Now, you’ll only occasionally see a few burps from the middle of the pool. Even so, it still discharges approximately 4,000 to 4,500 gallons of water every minute into the Firehole River.
The boardwalk splits at this point. Heading right will take you first past Turquoise Pool and then Opal Pool. Opal Pool tends to drain late in the summer season, and while both are very picturesque, they pale in comparison to Grand Prismatic Spring waiting at the top of the boardwalk. At roughly 300 feet in diameter, Grand Prismatic Spring is the third largest hot spring in the world. Its water is about 160 degrees Fahrenheit and it’s surrounded by orange and yellow thermophiles on a much larger scale than any other spring, emitting a fantastic display of color spanning much of the spectrum.
The thermophile bacterial mats extend under the boardwalk, so please do not disturb them. They are living organisms and it’s not worth killing them to write a temporary message that has no meaning for anyone but you. Also, don’t put your hand in the water along any boardwalk. Whether or not the water will burn your hand is irrelevant. It’s just plain disrespectful and completely unwelcome.
After passing by an abstract photographers paradise along the edge of Grand Prismatic Spring, the boardwalk winds back around to head back toward Excelsior Geyser Crater and rejoin the path where you came up.
From Old Faithful, head back onto the main highway and proceed north toward Madison. Just shy of six miles later, you’ll see the Midway Geyser Basin on your left. Park in the parking area and proceed to the bridge crossing the Firehole River.