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Named for the obsidian sand that is common throughout this basin, Black Sand Geyser Basin is home to a plethora of steaming geysers and hot springs. This quick, 0.4-mile boardwalk tour starts at the parking area just west of Old Faithful and heads southwest. In 35 feet, turn right to access an observation deck overlooking Cliff Geyser, a sporadic, crater-like geyser. Next, cross a footbridge over Iron Spring and turn left on the boardwalk that leads to the deep greens of Emerald Pool, one of the park’s most well-known hot springs. Finish off the tour at the aptly-named Rainbow Pool whose multi-colored waters are caused by algae and cyanobacteria.
MORE PARK INFO Yellowstone National Park, (307) 344-7381; nps.gov/yell/
-Mapped by Jeff Chow
- Distance: 0.6
Location: 44.4621992, -110.8535153
From the parking area, follow the path to the southwest. In 35 feet, turn right to access the observation deck for Cliff Geyser, a sporadic geyser that resembles a crater.
Location: 44.4618431, -110.8544433
Cross a footbridge over Iron Spring. The ruddy-colored banks of this creek are not caused by iron, but by reddish-brown algae that flourish in these thermal waters. Ahead, turn left onto the boardwalk that leads to the deep greens of Emerald Pool.
Location: 44.4610468, -110.8552587
One of the park’s most well-known hot springs, Emerald Pool’s color is created by the water’s blue reflection and the yellow algae that grows beneath the water’s surface.
Location: 44.4625878, -110.8548483
Examine the various shades of orange around the edges of Rainbow Pool (created by algae and cyanobacteria). Return to Waypoint 1.
Location: 44.4621724, -110.8538479
Location: 44.4621418, -110.853864
Location: 44.4619006, -110.85388
Location: 44.4610448, -110.8552238
Colorful Hot Springs
Location: 44.4621418, -110.8548
Sights at Black Sand Geyser Basin
Location: 44.4622547, -110.8548376
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Views of Cliff Geyser
Location: 44.462494, -110.8548832