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S TA R K & W I L D
grand
prismatic
spring
YELLOWSTONE NATIONAL
PARK, WYOMING
The Grand Prismatic Spring is a watery,
earthbound rainbow, a hot spring painted by
nature in its most brilliant colors. Diferent
microbes in the spring flourish at various tem-
peratures and assume pigmentation appro-
priate to their environment. Temperatures
at the center of the spring are too high to
support bacteria in any numbers, so the blue
is the blue of ordinary water and its selective
absorption of visible light. The science may
be prosaic—but the result is magical.
DON’T MISS
View the Grand Prismatic Falls on the easy Fairy Falls
Trail (2.5 mi/4 km), a two- or three-hour round-trip
from the trailhead on the park’s Grand Loop Road.
Take another hour to see Spray Geyser and Imperial
Geyser beyond Fairy Falls.
An aerial view of the multicolored Grand Prismatic
Spring, the largest hot spring in the United States