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![Grand Prismatic Spring in the Midway Geyser Basin amer0171.jpg Grand Prismatic Spring in the Midway Geyser Basin](/sites/default/files/styles/max_1300x1300/https/s3.amazonaws.com/s3-east-testmedia-noaa.woc.noaa.gov/dam/Photos/legacy/pl23_amer0171.jpg?itok=aY5f6KT1)
Description
Grand Prismatic Spring in the Midway Geyser Basin. This spring is the thirdlargest hydrothermal spring in the world, approximately 250 X 300 feet in sizeand about 160 feet deep. The water temperature is 160 F (70 C). The colors onthe edges of the spring are due to thermophile microbial mats that growin the mineral-rich waters. (Image credit: Dr. David Goodrich)